Fixed compilation of bitwise operators on oracle and sqlite.

Fixed compilation of bitwise operators on oracle and sqlite.

Implemented bitwise operators for Oracle which was previously
non-functional due to a non-standard syntax used by this database.
Oracle's support for bitwise "or" and "xor" starts with server version 21.
Additionally repaired the implementation of "xor" for SQLite.

As part of this change, the dialect compliance test suite has been enhanced
to include support for server-side bitwise tests; third party dialect
authors should refer to new "supports_bitwise" methods in the
requirements.py file to enable these tests.

Fixes: #11663
Change-Id: I41040bd67992b6c89ed3592edca8965d5d59be9e