feat(migrations): Prevent new migrations from using RunSQL

[wedamija]

This adds in allow_run_sql to our CheckedMigration baseclass. We want to prevent the use of RunSQL in most cases going forward, since our migration safety framework doesn't know how to parse sql to ensure safety.

Our main uses for this in the past were:

• Adding new columns with a default. We now can do this within the framework by using db_default instead of default.
• Deleting columns/tables. Since we have to remove from state, deploy, then delete we have to use raw sql to remove them from Postgres. I'll follow this up with a pr to provide ways to handle these deletions within our framework.

[wedamija]

Note that some tests will fail until we have a way to handle deleting tables/cols

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

Additional details and impacted files

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  Branches    20775    20775              
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+ Misses      62418    62398      -20     
  Partials      394      394