After 8.3 merge, gpdb has new polymorphic types, ANYENUM and ANYNONARRAY.

This fix adds support for ANYENUM and ANYNONARRAY in Translator.

As per postgreSQL, when a function has polymorphic arguments and results;
in the function call they must have the same actual type.
For example, a function declared as `f(ANYARRAY) returns ANYENUM`
will only accept arrays of enum types.

We already have this resolution logic implemented in
`resolve_polymorphic_argtypes()`.

Refactor the code in `PdrgpmdidResolvePolymorphicTypes()` to use
`resolve_polymorphic_argtypes()` to deduce the correct data type for
function argument and return type, based on function call.
Signed-off-by: NBhuvnesh Chaudhary <bchaudhary@pivotal.io>
Signed-off-by: NOmer Arap <oarap@pivotal.io>