Content Snapshot not populated when installing from configuration

I've made a few changes to the Merge Request as follows:

1. The form save operation didn't vary the bundle key while performing the EntityQuery, ensuring that entity types that didn't use bundle key type would throw an exception. This has been changed to use the bundle key provided by the entity.
2. Checks to make sure entities only get added to the snapshot queue once.
3. Ensures that entity update/delete hooks take the new config into account, thereby skipping entities that aren't set to be included in snapshots.