Arbitary type for optional column in enum tables

Right now enum [tables allow an optional column but the type of the optional column should be `text` ](https://hasura.io/docs/latest/schema/postgres/enums/#pg-create-enum-table)it would be nice to allow arbitrary type on the optional column.
There are many usages of that like saving additional data for the enum or use for custom sorting etc.

Start with the linked Hasura Postgres enum-table documentation and trace the implementation that restricts the optional column to text. Check the existing enum-table tests and determine how arbitrary PostgreSQL column types are represented and exposed. Done means supported types work for enum-table creation and their values remain usable for additional data or custom sorting.

Written by the indexing model from the issue text.