Add config error exception to handle 422 status code

[klaasnicolaas]

This allows us to catch the 422 status code and show a clear error message to the user from the API.

For example:

Traceback (most recent call last):
  File "/home/klaas/python-packages/forecast_solar/example.py", line 71, in <module>
    asyncio.run(main())
  File "/home/klaas/.pyenv/versions/3.10.6/lib/python3.10/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/home/klaas/.pyenv/versions/3.10.6/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete
    return future.result()
  File "/home/klaas/python-packages/forecast_solar/example.py", line 21, in main
    estimate = await forecast.estimate()
  File "/home/klaas/python-packages/forecast_solar/forecast_solar/__init__.py", line 161, in estimate
    data = await self._request(
  File "/home/klaas/python-packages/forecast_solar/forecast_solar/__init__.py", line 126, in _request
    raise ForecastSolarConfigError(data)
forecast_solar.exceptions.ForecastSolarConfigError: Invalid location, invalid plane definition or kWp == 0 (error 422)

[frenck]

Thanks, @klaasnicolaas 👍

../Frenck