Schema creation and end-to-end support

[LaurentRDC]

This is a pull request to ensure that we can:

• Create schemas (CREATE SCHEMA ...) in migrations using createDatabaseSchema;
• Drop schemas (DROP SCHEMA ...) in migrations using dropDatabaseSchema;
• Create tables with explicit schemas in migrations using createTableWithSchema;
• Add support for creating/dropping schemas in beam-postgres;
• Add tests to ensure that explicit schemas are supported by beam-postgres.

In the course of testing this, I also had to switch beam-postgres's test suite from using tmp-postgres (unmaintained) to testcontainers.

This pull request will remain in draft until I can confirm that these changes are working throughout

[LaurentRDC]

I have tested these changes on our production codebase and everything is working as expected, including migration and a wide variety of queries