Update NR P5 and P7 nFAPI headers to have 32-bit message_length
In the NR functions, this causes the header parameters following message_length to have their position shifted by 2 bytes, due to the increase in message_length size.

Change needed to accommodate SCF222.10.02 Table 3-3

Separates nfapi_p4_p5_message_header_t and nfapi_nr_p4_p5_message_header_t

Change the callbacks signature to accept/return void* intead of expecting a particular header type, being the NR/LTE distinction done inside the callback functions.

Create NR related functions for nFAPI transmit timestamp and checksum calculation.

Move nfapi_p7_codec_config_t and nfapi_p4_p5_codec_config_t to separate header to be shared between LTE and NR VNF/PNF

Move nfapi_nr_timing_info_t into NR header.

Move NR specific function declarations to NR header.