Take a snapshot of all models from the code base at the time when the
healing migration merges. The healing migration needs this frozen view
of the models to be available (even as the models change in the future)
to compare with the current DB schema. The healing migration will use
this comparison to heal the schema.
partially implement bp: db-migration-refactor
Change-Id: I438147c7961b1ecad47f6146cc7fc9396aee7bc5