ngap_pdu_t has the same definition as byte_array_t, so it is
replaced by the latter. This simplify the stack and reduces
duplicated code.
Also, add function create_byte_array to copy from an
existing buffer to a new byte_array_t and replaced
allocCopy with create_byte_array, and adopted
OCTET_STRING_fromBuf whenever possible.
Guido Casati
8fb8713023