Add more cross-type comparisons to contrib/btree_gin.

Add more cross-type comparisons to contrib/btree_gin.

Using the just-added infrastructure, extend btree_gin to support
cross-type operators in its other opclasses.  All of the cross-type
comparison operators supported by the core btree opclasses for
these datatypes are now available for btree_gin indexes as well.

Author: Tom Lane <[email protected]>
Reviewed-by: Arseniy Mukhin <[email protected]>
Discussion: https://postgr.es/m/262624.1738460652@sss.pgh.pa.us