Helper function for migrating to EmbeddedObject

[DominicFrei]

Goals

When migrating to EmbeddedObject two cases have to be handled:

• Objects without backlinks (orphaned objects)
• Objects with more than one backlink

This is necessary due to the nature of EmbeddedObjects always belonging to one and only one other object.

As explained in #2394 and #2393 this cannot be achieved while migrating because EmbeddedObject cannot be iterated over / queried since it's not a standalone object.

This will also unlock #2394.

Expected Results

• Orphaned objects get deleted automatically when a flag for deleting them is set as part of the migration block.
• Objects with multiple backlinks will be duplicated so that every object linking to them gets their own version.

[DominicFrei]

This will be unlocked by realm/realm-core#4729.

[sync-by-unito]

➤ Dominic Frei commented:

Unassigned myself and set it to Parked since we really don't know if and when we will do that. It's just an enhance to automate something that users can do manually anyway and it depends on a Core change that would have to be done first.

[softlion]

The core has been changed last year
realm/realm-core#5737

Also, how to do that manually as questioned here ? Can't find a way.
#2594 (comment)

[nirinchev]

This is now unblocked and we can pick it up.