- Added support for the Oracle table option ON COMMIT.  This is being
kept separate from Postgresql's ON COMMIT for now even though ON COMMIT
is in the SQL standard; the option is still very specific to temp tables
and we eventually would provide a more first class temporary table
feature.
- oracle can apparently do get_temp_table_names() too, so implement that,
fix its get_table_names(), and add it to #3204.  fixes #3204 again.