In case of false positive PDSCH CRC check, a random MAC PDU is processed.
Currently pdu_len is unsigned 16 Bit, so we did break out of the processing loop only if we _exactly_ hit a residual pdu_len of 0, or we hit a LCID of DL_SCH_LCID_PADDING.
If we didn't hit either of these, pdu_len wrapped to a very positive value, and we continued processing the PDU even beyond its bounds!
This behavior was observed with SNR 1 dB and MCS 9.

So better make pdu_len signed and break out of the loop after processing at max. pdu_len Bytes!

reworking of MAC functions to schedule SSBs, including VRB map occupation and get_type0_PDCCH_CSS_config_parameters

In FDD mode, the UE_mode switches to PUSCH mode before the initial TA value was applied.
Because of this, the ta_command was misinterpreted.
Fix this by adding 31 to the initial TA comamnd and handle it the same as TA updates.

This reverts commit 71e297de.

Even stricter check/hack for BWP ID.
Drop every DCI where this value is not '1'.

- temporary solution since scheduler does not support FDD
- modified is_NR_UL_slot to return always 1 when is FDD mode
- this is necessary because currently the scheduler assumes that is TDD
  and tdd_UL_DL_ConfigurationCommon is always initialied

Recently we stared using the BWP_indicator signalled in DCI, before we always assumed BWP_Id == 1.
Now "fake-DCI" with bandwidth_indicator == 0 lead to segmentation faults, so we discard these.
Note: There are still several placed where we assume BWP_Id == 1!

- this commit was necessary because the location of the MAC UE
  functions does not reflect the context in which they are used
- therefore all UL scheduling-related functions have been moved
  to a new nr_ue_scheduler.c file
- and the irrelevant file rar_tools_nrUE.c has been deleted
  (nr_ue_process_rar moved to nr_ue_procedures)
- the new locations are supposed to make the file and functions
  organisations more structured and cleaner

- new data structure RAR_grant_t to handle RAR grant
- new common ul scheduler function
- new common ul pdu configuration function handling ul grants
- new function to fill ul_config_request
- moved pdu configuration code from process dci function
- merged procedures for Msg3 and PUSCH together in nr_ue_scheduler
- the same functions are now handling both PUSCH and Msg3
- relying on ul_config (no more RA Msg3 frame and slot storage)
- done some cleanup and logging in the process

- this return whether the transform precoder is enabled or not
- redundant configuration code has been migrated to the new function
- get_transformPrecoding is a common MAC function used already
  @ UE side, can be adopted by gNB too

- this will be later be necessary in DCI procedures which are dependent on
  the RNTI type

- now transmitting resetting Msg3 slot and frame to -1 after transmission
- cleanup in Msg3 scheduling
- checked Msg3 pdu configuration against the 3GPP specs

- new data struct is RA_config_t
- all RA-related members have been moved to the new struct
- static variables have been migrated too

- sorted out according to recurring logic that wants function
  prototypes in separate files from data struct and constants
  definitions, variables in separate .c files with inclusion
  of "extern" header files
- moved function prototypes to resective header files
- moved data structures and constants to respective header files
- merged unnecessary mac.h file into mac_defs.h @ MAC UE
- moved const variables suchs as tables to respective .c files
- moved extern references to respective extern.h files

- related to section 5 of 3GPP TS 38.321 specs
- handling of RA failure
- handling of RA completion
- first implementation of contention-based RA procedures
- minor fixes related to ue_get_rach and init_ra functions

- enhancement of DL indication flow for Msg2 (RAR)
- merging interface procedures to handle DLSCH and RAR together
- better separation of MAC and PHY functionalities
- cleanup of double ambiguous functions to process RAR
- merging functions to process TA command into the ue_ta_procedures function
- enhancement of logging and formatting in the process

- as defined by clause 12 "BWP Operation" TS 38.213
- cleaned up hardcoded usage