Add a new scope data source (ueTimeDomainSamples) which provides time domain samples
for antenna 0 to the scope. Add graphical representation of the data in imscope.

Removed C-define from ENABLE_IMSCOPE cmake option, the #define was unused and this way
code does not have to be recompiled when imscope enable state changes.

Co-authored-by: Guido Casati <hello@guidocasati.com>

A new phy scope based on ImGui and ImPlot. This scope uses a different concurrency model than previous
scopes.

The PHY thread writing the data first checks if the data is ready to be written. If its not, nothing is copied.
The GUI thread reads data if available and marks it ready to write. This makes sure that the PHY threads are not
busy copying data that would never be displayed.

Some of the scopes also have a freeze functionality that further limit the amount of data that needs to be copied
from PHY threads. If a scope is "frozen" it still allows the user to explore the data using plots zoom/pan functions
but doesn't cause PHY threads to perform extra writes on the displayed data.

A compile option was added to enable/disable the scope. Use cmake -DENABLE_IMSCOPE=ON to enable the scope.

Update CXX standard to 17; it is required by some libraries (e.g., dear imgui). The oldest gcc version in
use by a distribution supported is Ubuntu 20, which has gcc 9.4 with c++17 support.

Before this commit, the following will trigger a complete rebuild:

- create another git name (git checkout -b test)
- run cmake again manually (cmake ..)
- run ninja again

The top-level CMakeLists.txt uses add_definitions() to add git
information to all targets; if some git information changes, this will
mark all command lines as dirty, triggering the build.

There is an easy solution: instead of passing this information on the
command line, pass it in a header. This commit uses configure_file() to
generate a file oai_version.h in the build directory with the same
information. Various sources files, e.g., main executables, use this to
output the same information as before. It is then also not necessary to
use header guards, as cmake takes care to create this file.

If cmake is re-run, it will update the header, and trigger only files
including this header will be rebuilt (which can be shown with the above
stpes). The information passed is the same as before, and updates the
information when the old method would have updated it.

This commit introduces google benchmark library and one benchmark for
rotate_cpx_vector.  Also extracted common tools used in testcases for
generation and allocation of byte aligned vectors in phy_test_tools.hpp

This creates another test executable for llr with the same testcases but compiled without avx 256-bit
vector instructions.

Remove openair1/SIMULATION/ETH_TRANSPORT/netlink_init.c, and move TUN
interface creation functionality to tun_if.c.

Remove SIMU_ETH target.

Move openair3/RRC/NAS/nas_config.c to common/utils/tun_if.c, and remove
the former from all targets.

I don't know about any user of the kernel modules. It is effectively
legacy code we carry around, for no good reason. Remove it for the
moment. If we ever need it, we can revert.

Remove netlink code, and the PDCP_USE_NETLINK macro, as there is no
known use, it makes the code more complicated, and is simply "technical
debt".

In 4G PDCP, a subtle change has been introduced, in pdcp_module_init()
of pdcp.c. Looking at the diff of this commit, it can be seen that there
is now a new "else-if (ENB_NAS_USE_TUN_W_MBMS_BIT)" branch that is under
what was the "if (PDCP_USE_NETLINK)" branch, while the code fragment was
actually inside the "else" branch of PDCP_USE_NETLINK. This seems to be
necessary: previously, if we did not use noS1 mode and we don't use any
TUN (i.e., the eNB), the else block would set up this interface. It is
important that this interface is brought up, because if we omit it,
RFsim will not work. It seems to me that this interface will regularly
create some traffic; without it, RFsim will be blocked, and the UE
cannot connect.

In short, it seems to be important to have the MBMS interface, which
injects traffic in the RFsim side, which will unblock RFsim. The change
in pdcp_module_init() preserves the total changes of the if-else
(PDCP_USE_NETLINK).

Add gold sequence cache with dynamic size, private to each thread. It
periodically reorders by call rate. To free the gold sequences after end
of life time of a thread, use the pthread API.

Extract thread-pool into a separate CMake library.
Extract utils into a separate CMake library.

Debian 11: cmake 3.18
Fedora 40: cmake 3.29
RHEL 9: installs cmake3, which is typically very recent, likely 3.29
Ubuntu 20: cmake 3.16

Ubuntu 18.04 is now in "Extended Security Maintenance", but otherwise
gets no updates. Remove it from supported distributions (regarding
installing packages); users can of course still use it.

Users are encouraged to upgrade to Ubuntu 20+.

Note: nr_fapi_p5 dependence in NFAPI_USER_LIB will be removed in a later commit

Properly add compile definitions related to aerial_lib into targets that  depend on it ( ENABLE_AERIAL )

Add target_compile_definitions to L2_NR library in order to propagate #define in gnb_config.c

	- Phy config update and Sidelink frame parameters initialisation
	- PSBCH scheduler to trigger TX PSBCH/RX PSBCH actions
	- Sidelink indication with rx ind to trigger send SL-MIB to MAC
	- Enable Scope for PSBCH use -d or --dqt
	- Enable system testing of PSBCH for example using RFSIMULATOR:

		- UE1 is a SYNCRONISATION SOURCE UE which transmits PSBCH

		  started using command -
		  sudo ./nr-uesoftmodem --sl-mode 2 --sync-ref 4 --rfsim --rfsimulator.serveraddr server

		- UE2 syncs onto UE1 during sidelink search, gets the timing and continues to receive PSBCH

		  started using command -
		  sudo ./nr-uesoftmodem --sl-mode 2 --rfsim --rfsimulator.serveraddr 127.0.0.1

		- In the default use case 2 Sidelink SSBs sent over 16 frames.

		- In case SL-SSB configuration needs to be changed use -O option in the above command like

		-O ../../../targets/PROJECTS/NR-SIDELINK/CONF/sidelink_preconfig_1txpool.conf

The library will be either found in the system or downloaded via FetchContent.

This commit introduces LTTng logging mechanism which is an open source
tracing tool.

URL: https://lttng.org/

SYS_NICE is a capability that allows a process to set thread affinity
and priority, among other things (see capabilities(7) for more info).

In this commit, add a function that allows to determine if the process
has this capability, and try to change the thread affinity and priority,
if requested. If the capability does not exist, the function will simply
not attempt to change the corresponding thread attributes.

To determine if the process has SYS_NICE, libcap can be used. However,
it might not be installed by default. To avoid requiring another
dependency, if we detect that libcap is not present, use a workaround by
try to set a real-time scheduling policy; if it's present, or can be
changed, we assume that the process has SYS_NICE (and clean up, if
relevant).

Simplify reading of capabilities

Use a common structure nr_lc_config_t to group LC configuration for one
logical channel. Use seq_arr for simple lookup, adding, removing of
elements without manual indexing logic.

This commit retains the previous logic of adding/releasing LCs through
the process_CellGroupConfig(), although we know while building the
CellGroupConfig if we add/release LCs. The next commit fixes this.

-rdynamic is necessary for clang as well to properly link shared
executables. Add furthermore an option to ignore unused command line
arguments, to suppress warning

  clang: warning: argument unused during compilation: '-rdynamic' [-Wunused-command-line-argument]

This is likely because -rdynamic is only relevant for the linker, but
the corresponding option add_link_options() is only available starting
cmake 3.13, while we are still at 3.12 (for Ubuntu 18, to my
understanding).