[Request] Add a `check` utility for test purposes

Basically similar to doobie's approach. Take a Query as an input, validate against a server connection that the query as written matches the types.

It shouldn't require inserting any rows, only that the tables involved exist.

Full-fledged integration tests for certain queries are often hard to write. They might involve many foreign key relations, and thus a lot of distracting and fiddly test setup, or they might be highly-parameterized queries (in terms of the sql structure - imagine a "list from table, maybe sort on a user-selected property, sometimes filter some other property by a user input, etc").

Start by reviewing the existing Query and server-connection APIs to determine how a query can be checked against PostgreSQL without executing inserts. Define the utility's supported validation behavior and confirm that completion means detecting type mismatches while requiring only that referenced tables exist; the issue names no files or tests to run.