Pass the domain in the plugin protocol #4483

What do you want to change?

Currently we the domain is not shared with the python sqlc plugin.
Ideally it would be possible to use this information to generate specific code depending on the domain:

CREATE DOMAIN job_status AS text
CHECK (
    VALUE IN (
                 'QUEUED', -- the job is in the queue and can be picked up if the dependencies are reached
                 'PENDING', -- the job is picked up, but the runner has not started it yet
                 'RUNNING', -- the job has been started by the runner the runner_info is provided
                 'COMPLETED', -- the job completed a result must be provided
                 'FAILED' -- the job failed a result must be provided
        )) NOT NULL;

ast should be passed to the plugin so we can emit a specific type instead of ANY:
https://github.com/sqlc-dev/sqlc-gen-python/blob/main/internal/gen.go#L683
https://github.com/sqlc-dev/sqlc-gen-python/blob/main/internal/postgresql_type.go#L45

So for the above case we could generate an enum. or atleast the type str or Literal['QEUEU', 'PENDING', ...]

What database engines need to be changed?

No response

What programming language backends need to be changed?

The protocol needs to be changed to include the domain.
Sqlc already parses domains in the AST.