Add rpi_power during onboarding on RPi

[MartinHjelmare]

Breaking change

Proposed change

• Add rpi_power during onboarding if Supervisor is set up and machine is RaspberryPi.

Todo

• Adjust frontend to not show integration selected during onboarding: Hide rpi_power entry during onboarding frontend#7001

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)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

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# Example configuration.yaml

Additional information

• This PR fixes or closes issue: fixes #
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Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
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• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

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

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  Updated and included derived files by running: python3 -m script.hassfest.
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  Updated by running python3 -m script.gen_requirements_all.
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[probot-home-assistant]

Hey there @shenxn, @swetoast, mind taking a look at this pull request as its been labeled with an integration (rpi_power) you are listed as a codeowner for? Thanks!
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