Add sensor unit of measurement validation for device classes

[frenck]

Proposed change

This PR adds validation for the units of measurement used by sensor entities when those entities have a device class.

Device classes limit their use of units, as documented in our end-user and developer documentation.

The idea is that this would help with strange/inconsistent occurrences and reduce the need to watch out for these things in code reviews.

In the future (e.g., 2023.6), we could change this to raise instead of a warning. Each warning is currently logged just once.

Example warning;

2022-12-21 13:08:06.195 WARNING (MainThread) [homeassistant.components.sensor] Entity sensor.today_energy (<class 'homeassistant.components.demo.sensor.DemoSumSensor'>) is using native unit of measurement 'cows' which is not a valid unit for the device class ('energy') it is using; Please update your configuration if your entity is manually configured, otherwise create a bug report at https://github.com/home-assistant/core/issues?q=is%3Aopen+is%3Aissue+label%3A%22integration%3A+demo%22

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
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• Tests have been added to verify that the new code works.

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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (sensor) you are listed as a code owner for? Thanks!

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[epenet]

Do we need to have the same validation for number entities?
And would it make sense to have this dict shared somewhere?

[frenck]

We have no validations on numbers whatsoever at this point. But yes, we can add more validation there too.

I suggest doing that at a later point.

Essentially, those are not the same device classes... (we can enforce keeping them in sync though)

[epenet]

I'm not sure if lm should be kept here. Lumen is a unit of Luminous flux, not a unit of Illuminance

I have opened an architecture discussion about it in home-assistant/architecture#843

[frenck]

This PR is not adding something new, the discussion is fine, but it doesn't have to block this.