Add support for packaged temporary table to metadata queries

[mrotteveel]

Firebird 6.0 introduces support for packaged temporary tables.

This requires some changes in Jaybird:

1. (with useCatalogAsPackage = false) metadata queries for tables/views and related objects (e.g. columns and indices) need to receive a RDB$PACKAGE_NAME is null condition.
2. (with useCatalogAsPackage = false) these metadata queries need to add the right conditions for searching in packages (or not).
3. Other queries for metadata and join conditions need to be reviewed. For example they may need a l.RDB$PACKAGE_NAME is not distinct from r.RDB$PACKAGE_NAME, and for example generated keys queries may need additional conditions to exclude packages, or search only packages, etc.
4. Extraction or parsing of table names from queries (e.g. for generated keys) may need some rework to account for this additional object name in the object reference (identifier chain).
5. Possibly other things I didn't think of.

The metadata queries may also need to consider the RDB$PRIVATE_FLAG column to only query public tables (unfortunately, that column is NULL for non-packaged tables).