Support realtime scheduling for add-ons

[pvizeli]

Proposed change

Add new add-on option: realtime: bool

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality to the supervisor)
• 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: Add-on option realtime developers.home-assistant#816

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.
• I have followed the development checklist
• The code has been formatted using Black (black --fast supervisor tests)
• Tests have been added to verify that the new code works.

If API endpoints of add-on configuration are added/changed:

• Documentation added/updated for developers.home-assistant.io

[frenck]

Awesome!

[jens-maus]

Yeah thanks for getting this integrated. Hope to see it integrated together with home-assistant/operating-system#1236 soon in a new public supervisor version. Any ETA for users?