[FEATURE]: Dynamic Schema

### Describe what you want

It doesn't seem possible to use `pgSchema` or related with dynamic runtime values. (https://orm.drizzle.team/docs/schemas)
in #423, proposed solutions use a table factory to achieve this, and while this works with the query builder (with code duplication and bad DX), this is not viable for use with relational queries or drizzle-kit.

It is very common to use schemas for separating tables of different tenants in multitenant applications. The easiest way to support this would probably be with an addition to the `drizzle()` function, which could take an optional schema argument. The schema would apply to all the tables defined on the drizzle db instance.

Similarly, optional config with drizzle kit to specify a schema would solve the problem.