[1.7.x] Fixed #23611 -- update_or_create failing from a related manager

Added update_or_create to RelatedManager, ManyRelatedManager and
GenericRelatedObjectManager.
Added missing get_or_create to GenericRelatedObjectManager.

Conflicts:
	tests/generic_relations/tests.py
	tests/get_or_create/tests.py

Backport of ed37f7e979 from master