Problem/Motivation
This is a part of #2960253: [meta] Allow Paragraphs widget/field and similar use cases to to be considered translatable which is being split into 3 separate issues and converted to a meta issue.
* While we don't want the paragraph field values to be replaced, we basically need to be able to apply the same/similar logic to our referenced entities. So when a new "merge-revision" of the node is created, we want to do the same to the paragraphs, so that they too merge their translatable/untranslatable fields together. And later on when we have fancy conflict resolution that will replace this special case, we'll need to be able to apply that recursively as well.
Proposed resolution
Add hook_entity_revision_create() and hook_ENTITY_TYPE_revision_create()
Remaining tasks
User interface changes
None
API changes
Two new hooks, no changes.
Data model changes
None.