Add nilu air_quality platform

[hfurubotten]

Description:

New platform in the air_quality platform. Shows data from the governmental air research institute sensor stations within Norway.

Rewritten from a sensor platfrom to air_quality platform. Original PR here: #18104

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#7993

Example entry for configuration.yaml (if applicable):

air_quality:
  - platform: nilu
    show_on_map: True
  - platform: nilu
    show_on_map: True
    area: Bergen

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

[MartinHjelmare]

Looks good!

[MartinHjelmare]

Looks good!

[MartinHjelmare]

Let's wait here until we know if #19448 should be merged first.

[MartinHjelmare]

#19448 has been merged so we need to rebase and move this platform under the air_quality component.

[hfurubotten]

It should be rebased and moved to the air_quality component now.
Please check that everything is as it should. Got myself into trouble when rebasing, but I think I have gotten everything into order. However a double check would be nice.

[MartinHjelmare]

There should preferably not be a unit of measurement but that should be standardized. Maybe we haven't done that yet? @fabaff

[hfurubotten]

Is it possible to add a property where it gives the unit of measurement, such as on sensors? I was not sure if all measured components should be defined in µg/m³, so I added it to the output of each.

All measured pollutants currently supported from the NILU-client is measured in µg/m³ or mg/m³, so one fit it all is possible with what the air_quality component gives of information now. CO/carbon monoxide is the one thats measured in mg/m³, but this can easily be converted to µg/m³ to get a one fits it all.

Can add this to the platform:

    @property
    def unit_of_measurement(self) -> str:
        """Return the unit this state is expressed in."""
        return 'µg/m³'

[fabaff]

There should be no unit of measurements because the frontend should take care about this.

[hfurubotten]

I will fix the output. What is the default unit the frontend expect, so I can make sure they are correct or converted?

[MartinHjelmare]

Besides the property units this looks good! I'd like @fabaff to comment about that, if there's a plan/spec for that, before we merge.