Merge remote-tracking branch 'origin/NR_RRCConfiguration_sync_source' into develop_integration_2020_w15_bis

This refactors the preprocessor. The new preprocessor implements the
same scheduling strategy (Modified Round-Robin: give resources according
to round-robin, then group) but should be fairer by changing every time
the RR start UE (i.e., 1st TTI UE 0 starts, 2nd TTI UE 1, etc) when the
UE number is not a divisor/multiple of the RBG size (and the last RBG is
often smaller). This also removes all unneeded code of the preprocessor
such as allocate(), positioning(), etc.

* do not check rlc_ind()
* Simplify retransmission part and remove nb_rb_available var
* Simplify new transmission code
* Simplify fill_DLSCH_dci(), avoid unnecessary copies
* fix: first check No. RBs, then check CCE alloc

Previously, the various rlc_*_ind() functions had a parameter to enable
the MAC to specify the max TB size that a subsequent call to the
corresponding rlc_*_req() (!) function would return. This patch removes
this parameter from the rlc_*_ind() functions and makes the parameter
working that is already in the rlc_*_req() functions.

store_dlsch_buffer() puts the RLC buffer status results in the
UE_TEMPLATE, which is per-CC. Since the DLSCH scheduler works per-CC,
too, we pass the right CC. However, this is not strictly necessary, as
we could do this once before every CC, and it might be updated.

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

UE_list_t is now used as a separate list. It can be e.g. used in the
scheduler to mark groups of users. The original UE_list_t is renamed to
UE_info_t to reflect that it is a container for information about UEs.