Properly sending DL ACK/nACKs

See merge request aburger/openairinterface5g!113

This commit include dynamically setting the slots_per_frame
value based on configuration. It also includes some comments.
Lastly, simplified bug fix in MAC layer related to sched_frame
calculation.

Using message_id to identify channel info.

See merge request aburger/openairinterface5g!114

These allow the NRUE to reach roughtly 15-25 Mbps
with ~20%-34% packetloss without crashing.

Previously, we thought the memset in the nr_ue_dl_indication()
was causing issues / exposing a race. This is not the case. The
memset is not problematic, the issue is that in the emulate_l1
mode we were not always configuring the DCI nbits before handling
the DCI when we are pushing high (15 Mbps) throughput traffic.

Also, properly filling the CCE index and Agg level
in the stub function when we get the DCI from
nfapi

Instead of conditionally calling the pucch_scheduler
we now only call the functions we need from the stub
function directly. This is better because we are not
modifying the OAI MAC layer code and ensuring that we
are not calling the pucch_scheduler twice for the same
sfn/slot

This is what we did in the NRUE for NSA mode

Adding error checking before indexing in mac layer harq array
Adding error checking before writing ul_harq_sfn_slot
Added comments
Made a "static" free_uci_inds() actually static

This reverts commit 9a78b589.

The nfapi code releases dl_ttis and tx_data_reqs
if the buffer has data in it. In the proxy code we
overwrite this instead of dropping the packet.

The timing advance field could be abstracted in
the proxy gNB. Currently we are not abstracting
this value.

Attempting to manually cherry-pick this commit:
30c14c2f

nfapi.c: Add on_error()

See merge request aburger/openairinterface5g!96

If we dont have this break we are trying to queue
the UL_TTI_REQ we just queued

We have gotten rid of filling the ACK/NACK with
the DLSCH and now only fill with the PUCCH. This
assumes that the MAC layer is properly decoding the
dl_tti_req and tx_data_req and allows us to
simply use the MAC layers scheduled SNF/Slot
to return the ACK NACK. There are some hacks added
in this commit which ensure that the PDCP packet
has the correct header (1st byte = 80) and now with
15Mbps we are seeing about 20% packet loss and
a gNB bug on the edge case (current frame is 1023
and the gNB schduler wants an ACK in frame 0 but the
scheduled UL_TTI_REQ has a frame of 1023).

Several of these changes were made previously and
lost in the merge.

This now matches the develop branch as well.

We should be setting the queued UCI indication slot
based on the SCHEDULED slot, not the current slot.

Added NR to NUM_MCS for nr channel modeling.

See merge request aburger/openairinterface5g!109

Removed strange characters in the first line.

See merge request aburger/openairinterface5g!108