CAST the elements in ARRAYs when using psycopg2

CAST the elements in ARRAYs when using psycopg2

Adjusted the psycopg2 dialect to emit an explicit PostgreSQL-style cast for
bound parameters that contain ARRAY elements. This allows the full range of
datatypes to function correctly within arrays. The asyncpg dialect already
generated these internal casts in the final statement. This also includes
support for array slice updates as well as the PostgreSQL-specific
:meth:`_postgresql.ARRAY.contains` method.

Fixes: #6023
Change-Id: Ia7519ac4371a635f05ac69a3a4d0f4e6d2f04cad