add addMissingSchemaFields task

[haroun]

Summary

Adds @apostrophecms/migration:add-missing-schema-fields task

What are the specific steps to test this change?

1. Go to the Checks tab, all tests must be green.
2. Manually test @apostrophecms/migration:add-missing-schema-fields and @apostrophecms/migration:migrate tasks maybe.

What kind of change does this PR introduce?

(Check at least one)

• Bug fix
• New feature
• Refactor
• Documentation
• Build-related changes
• Other

Make sure the PR fulfills these requirements:

• It includes a) the existing issue ID being resolved, b) a convincing reason for adding this feature, or c) a clear description of the bug it resolves
• The changelog is updated
• Related documentation has been updated
• Related tests have been updated

If adding a new feature without an already open issue, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

[linear]

PRO-8358 Allow our logic that adds missing defaults for new properties to run separately as a command line task without running migrations at the same time.

[haroun]

Recreating the section because this is not part of today's release, easier for me to handle future conflict.

[boutell]

Minor change request

[boutell]

You should skip this line too, even though it means your task will have to explicitly call addMissingSchemaFields.

This is appropriate because:

• We used the before hook to implement addMissingSchemaFields, which is a special kind of migration
• Other people and other modules will likely do the same thing
• Michelin doesn't want anything else that smells like a migration at all to happen in this task.

[haroun]

Regarding the following code

    await self.apos.lock.withLock('@apostrophecms/migration:migrate', async () => {
      await self.apos.migration.migrate(self.argv);
      // Inserts the global doc in the default locale if it does not exist;
      // same for other singleton piece types registered by other modules
      for (const apostropheModule of Object.values(self.modules)) {
        if (self.instanceOf(apostropheModule, '@apostrophecms/piece-type') && apostropheModule.options.singletonAuto) {
          await apostropheModule.insertIfMissing();
        }
      }
      await self.apos.page.implementParkAllInDefaultLocale();
      await self.apos.doc.replicate(); // emits beforeReplicate and afterReplicate events
      // Replicate will have created the parked pages across locales if needed,
      // but we may still need to reset parked properties
      await self.apos.page.implementParkAllInOtherLocales();
    });

Should I skip all apostropheModule.insertIfMissing + page.implementParkAllInDefaultLocale, doc.replicate & page.implementParkAllInOtherLocales too?

[boutell]

Yes, that makes sense.

[boutell]

I see why you did this, but previously, these "requirements" were guaranteed to come last, even after the after event. And changing that is an unnecessary risk.

So, please make them individual handlers on a new requirements event which is fired after the after event has been safely awaited.

[boutell]

Emit a new requirements event "after after" 😄