Move functorch tests from functorch/test/* to test/functorch/* (#86623)
This is the first step described in
https://github.com/pytorch/pytorch/issues/86618 . test/functorch/* is
the final location for these tests.
Test Plan:
- Check that the functorch shards in CI are still running tests.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86623
Approved by: https://github.com/huydhn
