Add QuatDescriptor descriptor and QuatLike type alias

[taldcroft]

Description

Similar to https://github.com/sot/cxotime/pull/43, this adds a descriptor that facilitates make a dataclass with a Quat attribute initialized from a QuatLike input.

Requires

• https://github.com/sot/ska_helpers/pull/53

Interface impacts

None except adds QuatDescr and QuatLike to the public API.

Testing

Unit tests

• [x] Mac

  
  (masters) ➜  Quaternion git:(quattype-descriptor-quatlike) git rev-parse HEAD  
  af603055c2be847493ed9a95165d993324d1eedf
  (masters) ➜  Quaternion git:(quattype-descriptor-quatlike) pytest
  ===================================================== test session starts =====================================================
  platform darwin -- Python 3.10.8, pytest-7.2.1, pluggy-1.0.0
  rootdir: /Users/aldcroft/git, configfile: pytest.ini
  plugins: timeout-2.1.0, anyio-3.6.2
  collected 72 items                                                                                                            

Quaternion/tests/test_all.py .............................................. [ 63%] Quaternion/tests/test_shaped.py .......................... [100%]

===================================================== 72 passed in 2.89s ======================================================

Independent check of unit tests by [REVIEWER NAME]
- [ ] [PLATFORM]:

### Functional tests
<!-- Describe and document results of any functional tests, otherwise leave the text below -->
No functional testing.