Separate nfapi_p5.c into LTE and NR implementations.
This MR aims to separate the implementation of the nFAPI P5 and P7 message pack/unpack procedures into 4G and 5G implementations.
This will be followed up with a separation of the VNF and PNF implementations in 4G and 5G versions as well.
The final goal is to achieve a clean separation between 4G and 5G, foregoing the need to compile 4G components when we only want to compile 5G ones.