API response recorder for test fixtures

[gouline]

API test fixtures are responses saved from an old Metabase release with rough manual additions over the years. To be able to create reproducible test cases for current Metabase releases, there needs to be a way to re-generate these as needed.

• API response recorder to generate repeatable test fixtures
• Migrate sandbox Metabase to H2 database mounted as a local volume that can be committed to preserve test questions and dashboards (bootstrapping anything mildly complex via API is too hard, that area is largely internal to Metabase and changes without warning)
• Create and commit a representative selection of collections, dashboards and questions (query tables, query questions, native SQL queries)
• Generate new fixtures and fix breaking tests