move db migrations inside the uffd folder

MANIFEST.in

uffd/__init__.py

uffd/migrations/README

uffd/migrations/alembic.ini

uffd/migrations/env.py

uffd/migrations/script.py.mako

...ions/2a6b1fb82ce6_added_missing_oauth2grant_code_index.py

uffd/migrations/versions/54b2413586fd_invite_pk_change.py

uffd/migrations/versions/5a07d4a63b64_role_inclusion.py

...s/5cab70e95bf8_invite_creator_and_role_moderator_group.py

uffd/migrations/versions/a29870f95175_initial_migration.py

uffd/migrations/versions/a594d3b3e05b_added_role_locked.py

uffd/migrations/versions/a8c6b6e91c28_device_login.py

...migrations/versions/aff5f350dcdf_added_role_is_default.py

.../bad6fc529510_added_rolegroup_requires_mfa_and_cleanup.py

...migrations/versions/cbca20cf64d9_constraint_name_fixes.py