Call __builtin_popcountll function to count the number of bits set in uint64_t variable for polar codes

Testing on Neoverse N1 (Ampere 3GHz). Tested only on a subset of phy-simulators.

- Changes:
- use SIMDE consistently
- adaptations of LDPC decoder generator for ARMv8 performance
- SIMDe modifications of Intel CRC to allow for aarch64 build.
  optimizations for 128-bit to improve performance of LDPC encode/decode
  on aarch64 (Neoverse 1)
- added BG2 files for 128-bit ldpc encoder (aarch64)
- testing on Xeon
- testing on x86
- minor changes to build/run on x86
- change in crc.h after returning to aarch64
- removed some warning in ldpc decoder generator for x86_64
- char
- Delete irrelevant constants
- Correctly declare variables
- Define stdbool for all architectures
- Remove definition of _MM_SHUFFLE and use SIMDE_MM_SHUFFLE
- Remove commented code
- Fix CMakeLists.txt
- Include SIMDE avx2 functions in tools_defs.h

- Global variables that are never written to are marked const
- Remove some EXTERN declaration
- Remove unused `log_mem_multi` from logging module

To use c16maddShift(), c32x16maddShift(), c16multaddVectRealComplex(), and c16x32div() functions in nr_pdsch_channel_estimation()

changes to support 768-point DFT/IDFT, renaming of 768-point DFT for DFT-precoding (4 DFTs per call)

(cherry picked from commit de93d8f0aa9e6d7380bd159901a41aa36f257298)

This commit contains work done by Eurecom and by Benetel.