This change is done in preparation to add the header unpack functions to the VNF and PNF structures as function pointers, used to peek the message headers prior to processing.
Add a faux fapi_nr_p7_message_header_unpack with the same signature as nfapi_nr_p7_message_header_unpack, to be used for the P7 header unpack function pointer.
Changed parameter of unpack_nr_rx_data_indication to void* to be inline with other unpack procedures.
Changed nfapi_p7_allocate calls to calloc to avoid dependency from FAPI lib to nFAPI lib.
Add unitary test for RX_DATA.indication( test pack/unpack, free, copy and compare )