Allow custom code and related blueprints to be migrated from one project to another.

Currently, after migrating a blueprint that is based on a code class to a new project, the blueprint breaks due to unknown parent ([Link Removed])

Migrating & copy/pasting the code along with the blueprint still causes the BP parent to become unset after migration and the blueprint is unusable.

1. Open UE4 Editor (any project - Project1)
2. Add code to project based on actor (MyActor)
3. Add new blueprint based off of MyActor (MyActorBP)
4. Save project
5. Create another project (Project2)
6. In Project1, right click MyActor and select Asset Actions->Migrate
7. Migrate MyActorBP and related assets to MyProject2

Result:
Blueprint has no reference to its parent after migrating and cannot be opened. This occurs even if the code class is copy/pasted into the second project before migrating the blueprint

Expected:
Migrating code/blueprints from one project to another update references to the new project

Repro Rate:
3/3