feat: Add database fixtures for testing migrations

[mafredri]

This PR adds two types of fixtures for testing database migrations

1. Incremental fixtures in coderd/database/migrations/testdata/fixtures
2. Full deployment fixtures in coderd/database/migrations/testdata/full_dumps/vX.X.X

For 1), the purpose of the fixtures folder is for us to incrementally add data we feel should be tested during a migration, it's based on a complete dump, but the idea is to evolve it via manual additions (see 000024 example).

For 2), the purpose is for us to easily take a specific version of Coder, create a deployment, dump the database, and ensure that this deployment upgrades without issue for all eternity.

TODO

• Documentation
  • Describe the logic behind 000022 in file names and how to add fixtures
  • Describe how to create full dumps
• (In this or future PR) Checks to ensure new tables are populated with data?

Questions

Thoughts on where to place the documentation?

• https://coder.com/docs/coder-oss/latest/CONTRIBUTING ?
• A README.md in coderd/datdabase/migrations?

[kylecarbs]

I enjoy the automated nature of this - it'll just tell us when we broke prior versions!

How do you imagine we'll promote devs to add a new dump or fixture?

[mafredri]

@kylecarbs with 7d1c3e8 it looks like this:

❯ go test ./coderd/database/migrations -run=TestMigrateUpWithFixtures
--- FAIL: TestMigrateUpWithFixtures (0.00s)
    migrate_test.go:257: The following tables have zero rows, consider adding fixtures for them or create a full database dump:
    migrate_test.go:258: tables have zero rows: [audit_logs git_auth_links group_members licenses replicas]
    migrate_test.go:260: See https://github.com/coder/coder/blob/main/docs/CONTRIBUTING.md#database-fixtures-for-testing-migrations for more information
FAIL
FAIL	github.com/coder/coder/coderd/database/migrations	7.608s
FAIL

[mafredri]

This PR is now pretty much complete:

• We have docs for adding fixtures
• We detect if new tables are added without fixtures and return a descriptive error

The only remaining issue would be to improve how fast a user might run into the migration/fixture error, but I think we can improve that when/if it becomes annoying.

@bpmct would love your input on this (esp. the docs part).