Support uuid type in Postgres

[bporterfield]

What happens?

It's not uncommon to use uuid for primary keys, should be simple to support but not supporting means some annoying casting and confusing error messages

To Reproduce

create table with uuid, note that it is not a supported type in malloy, encounter various error messages

OS:

any

Malloy Client:

any

Malloy Client Version:

any

Database Connection:

Postgres