[FEATURE] : Support User defined Types

[bheemvennapureddy]

Describe the feature
Support User defined types

https://www.postgresql.org/docs/current/xtypes.html

Example :

CREATE TYPE udt_KeyValue AS (
    Key INT,
    Value VARCHAR(1000)
);

*Motivation

PGSQL does not support user-defined table types, but it does support user-defined data types. we use them to store csv data in user defined types and refctor them

[bplunkett-stripe]

This should be pretty straightforward to implement I believe.