* MM-9728: Online migration for advanced permissions phase 2
* Add unit tests for new store functions.
* Move migration specific code to own file.
* Add migration state function test.
* Style fixes.
* Add i18n strings.
* Fix mocks.
* Add TestMain to migrations package tests.
* Fix typo.
* Fix review comments.
* Fix up the "Check if migration is done" check to actually work.
