L2SS-1492: MultiStationObservation and StationObservationFuture change spec handling

.gitignore

README.md

docs/cleanup.sh

lofar_station_client/observation/constants.py

...r_station_client/observation/multi_station_observation.py

lofar_station_client/observation/station_observation.py

..._station_client/observation/station_observation_future.py

pyproject.toml

setup.cfg

test-requirements.txt

tests/observation/specs.py

tests/observation/test_multi_station_observation.py

tests/observation/test_station_observation_future.py

tox.ini