bugfix/cleanup: remove uint8_t to encode size plus some cleanup

The starting point was the function do_NR_DLInformationTransfer() which
may deal with more than 256 bytes.

Then why not cleanup all the functions in the same file.
(And do a bit of formattting fixing while we're here.)

Then cleanup the callers of those functions.

Then, because of do_SIB23_NR() let's also cleanup in some
structures.

Not all the codebase was cleaned up, there surely remain some uint8_t
(and char/short/uint16_t) which are wrong.