misc: add parts for flightrec reader in EE

This includes:
- Call flightrec Lua C initialization.
- Stop exporting in public API flightrec configuration function. It
is intended for private use.
- Export iproto_key_translation for representing requests/response
records.

Part of https://github.com/tarantool/tarantool-ee/issues/319

NO_TEST=preparation for EE changes
NO_CHANGELOG=preparation for EE changes
NO_DOC=preparation for EE changes