Move decision of Msg2 allocation time instant from instance we receive
RA indication (only containing preamble time information) to actual RA
scheduler (containing current DL slot time). This has the advantage:

- if Msg2 cannot be sent, we might try in a later slot
- no timing-based problems were a RACH.indication FAPI message might
  come late, we calculate a Msg2 frame/slot, but this instant has
  already passed in the DL scheduler
- no assumption about slot_ahead (an L1 constant)

The previous code calculated and verified an SSB index; I am not sure
this code is correct or used. I leave the function
ssb_index_from_prach() (hence the gcc attribute), but remove any checks.
Similarly, the beam association list might be wrong. I deleted the
corresponding code.

- the preamble is needed to detect when we are outside of the RA window,
  so store it
- store the rest of Msg1 variables together in struct

- create function to find free RA process
- reorganize function to put Msg1 related processing first, Msg2 second

Before this commit, there was data that was not initialized, resulting
in Msg2 remaining unscheduled.

Integration `2024.w13`

Closes #696 and #762

See merge request oai/openairinterface5g!2653

* !1911 Preparatory work for NR DL 4-layer MIMO at gNB
* !2610 fix ug on pilot 2 in nr_pbch_dmrs_correlation() that is lacking signal...
* !2639 NR gNB PUCCH2 CQI workaround
* !2642 NR UE demoting to LOG_D another log that cause flooding
* !2644 NR UE prevent segfault at detach
* !2645 add error code for pdu session reject in the ue
* !2600 Handle Msg3 with SRB1 RRCReestablishmentComplete and MAC CE C-RNTI
* trigger RF-sim E1+F1 test without asan
* !2636 Fix various F1 problems
* !2641 NR DL and UL channel estimation fix
* !2652 Provide additional troubleshooting documentation for QtScope
* !2646 NRUE fix asn_sequence_del to clear a list
* !2504 CI: use iperf3, refactor Iperf_Module
* !2617 use UE ID instead of RNTI internally in NR RLC
* !2619 Minor PDCP fixes
* !2648 Minor CI fixes, stack protection, fix E1+F1 Quectel test, L2sim5G test

Merge remote-tracking branch 'origin/NR_UE_fix_wrong_use_asn_sequence_del' into integration_2024_w13

Merge remote-tracking branch 'origin/NR_fix_layer_port_confusion_channel_estimates' into integration_2024_w13

Merge remote-tracking branch 'origin/Fix_Msg3_RRCReestablishmentComplete_with_C-RNTI' into integration_2024_w13

Merge remote-tracking branch 'origin/demote_another_log_printed_too_many_times' into integration_2024_w13

On Wayland (e.g., Gnome on Ubuntu 22), additional steps might be
necessary to make QtScope run. Describe them in the doc.

Closes: #696

- this prevents pulling PDUs from PDCP when re-establishment is awaiting

- short and long SN sizes
- PDCP PDU header sizes
- PDCP integrity size
- getter for maximim PDCP PDU size

From 3GPP TS 38.321 Section 5.4.3 Multiplexing and assembly, we need to process the highest priority subPDUs first:
- MAC CE for C-RNTI is the one with higher priority

38.473 section 8.2.3.1 says that upon F1 Setup Request, UE associated
signalling should be erased. In this commit, we trigger a release of all
UEs that were still connected to a DU when we received the SCTP
shutdown, i.e., when the DU disconnects.

Closes #762

Explanations: see #706. TLDR: the RRC code calls nr_pdcp_remove_ue(), so
we should not call it in the E1 handler if we do not use split mode.