sql: support user-defined types

[knz]

ie. CREATE TYPE T AS ... and CREATE DOMAIN T AS

Multiple variants:

• CREATE TYPE: composite types sql: support user-defined composite/record types #27792
• CREATE TYPE: enum types sql: support ENUM types #24873
• CREATE TYPE: range types sql: support RANGE types #27791
• CREATE DOMAIN: domain types sql: support user-defined DOMAIN types #27796
• CREATE TYPE: custom base/primitive types sql: support custom/user-defined base scalar (primitive) types #27793

Special note:

Whenever a user-defined type is created (with CREATE TYPE), PostgreSQL automatically creates an associated array type, whose name consists of the element type's name prepended with an underscore, and truncated if necessary to keep it less than NAMEDATALEN bytes long. (If the name so generated collides with an existing type name, the process is repeated until a non-colliding name is found.) This implicitly-created array type is variable length and uses the built-in input and output functions array_in and array_out. The array type tracks any changes in its element type's owner or schema, and is dropped if the element type is.

Jira issue: CRDB-5728

[tlvenn]

One user defined type that is super common with Postgres is the Money compound type, defined as such:

CREATE TYPE public.money_with_currency AS (currency_code char(3), amount decimal);

It would be super useful to be able to define this with CRDB.

[ketzacoatl]

Support for CREATE DOMAIN / domain types (#27796) is necessary for CockroachDB to be available to haskell web services written with the Yesod web framework.