feat: add reader for AMES lev0 data

docs/source/api/index.md

docs/source/api/readers.md

src/cigas_ptrms/readers/__init__.py

src/cigas_ptrms/readers/ames.py

src/cigas_ptrms/utils.py

tests/ames/test_ames.py

tests/conftest.py

tests/data/lev0/ref_lev0.nas