Add light platform to Linear

[IceBotYT]

Proposed change

Adds the light platform to Linear. These are not separate lights, but only lights that are inside of garage door openers.

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [x] 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 #
• This PR is related to issue:
• Link to documentation pull request: https://github.com/home-assistant/home-assistant.io/pull/31618

Checklist

• [x] The code change is tested and works locally.
• [x] Local tests pass. Your PR cannot be merged unless tests pass
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• [x] Tests have been added to verify that the new code works.

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  Updated and included derived files by running: python3 -m script.hassfest.
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[joostlek]

I do like the base entity, so if you can maybe open a separate PR to do that before we merge this PR, that'd be nice :)

[IceBotYT]

Done #116133