Feature: bootstrap operations

[mfridman]

In many systems, it's quite common to have migration(s) that insert some piece of data that should always be there, such as reference tables or an admin user.

However, when you squash migrations, you need to remember those bespoke migrations and include them in the final squashed migration file.

The alternative solution is to build some tooling that does this at application startup.

I wonder if there's an elegant solution here for goose to manage these sorts of "data migrations" outside the normal schema changes.

Related:

• Support repetable migration #108
• Ability to add repeatable SQL migrations #472