gbak: Document -INCLUDE_DATA switch

[mrotteveel]

Firebird 4.0 introduced the -INCLUDE_DATA switch for gbak (https://www.firebirdsql.org/file/documentation/release_notes/html/en/4_0/rlsnotes40.html#rnfb40-util-gbak-include-data). This is not yet documented in the gbak docs.

Also check for other missing switches.