Pass DDLCompiler IdentifierPreparer to visit_ENUM

Pass DDLCompiler IdentifierPreparer to visit_ENUM

Fixed issue where the "schema_translate_map" feature would not work with a
PostgreSQL native enumeration type (i.e. :class:`.Enum`,
:class:`.postgresql.ENUM`) in that while the "CREATE TYPE" statement would
be emitted with the correct schema, the schema would not be rendered in
the CREATE TABLE statement at the point at which the enumeration was
referenced.

Fixes: #5158
Change-Id: I41529785de2e736c70a142c2ae5705060bfed73e