Adds ability to apply migrations without versioning

[mfridman]

Closes #259.

This implementation adds no-versioning support to all existing commands, effectively treating the provided directory as a source of truth. There should be no behaviour changes to existing (versioned) migrations.

No version means "apply migrations without tracking them in the schema table".

A common use case might be (see linked ticker for even more context):

1. Apply versioned migrations
2. Apply not versioned seed data (from a different directory)
3. Reset the database by migrating all the seed data down

There are some limitations of no-versioning because we're not storing the history of applied migrations. Example:

Say you have 5 seed migrations and are running the following commands repeatedly: down will only ever apply the last migration down. Running up-by-one will only ever apply the first migration up. Also, running up-to and then a down-to won't work, since all unversioned migrations start at either the first or last migration.

This limitation is expected, and most users will likely run up followed by reset with the --no-versioning flag (CLI) or WithNoVersioning() library functional option.

• Fix output to make sense when versioning is disabled
• Add e2e tests for seeding / checking both up and down commands