Test that migrations are marked as repeatable

[mlocati]

When we create a new migration, 99% of times it is repeatable, so let's add a test case to check this.

This new test case checks that all migrations are marked as repeatable, except the ones explicitly listed in the $allowedNotRepeatableMigrations property of this new RepeatableMigrationsTest test.

This new test case helps a lot avoiding problems like these:

• Mark migration 20180123000000 as repeatable #6382
• Add publish end date functionality #6475 (review)
• Add Force Check-In Tools and Button #6539 (review)
• Mark migration 20180328215345 as repeatable #6636

Marking migrations as repeatable is very important, because the --rerun option of the c5:update command can re-execute migrations only if they are repeatable, and all the next migrations are repeatable.
For instance, if we have migrations M1, M2, M3, M4, M5, and M3 is not marked as repeatable, the --rerun option will let you rerun only re-execute migrations M4 and M5.

PS: this PR should fail, since #6636 is not merged yet.

[mlocati]

PS: this PR should fail, since #6636 is not merged yet.

And here's the expected error message shown by this new test:

These migrations should implement the \Concrete\Core\Updater\Migrations\RepeatableMigrationInterface interface (if they are repeatable)
or they should be listed in the $allowedNotRepeatableMigrations variable of the file tests/Update/RepeatableMigrationsTest.php (if they are not repeatable):

• Concrete\Core\Updater\Migrations\Migrations\Version20180328215345

#6636 will fix this.