Add yamllint (in pre-commit and CI)

[frenck]

Proposed change

Add yamllint to pre-commit and CI.

I've adjusted all existing YAML files to make it pass.
It runs in under a second (all files) and in general use with pre-commit, it only triggers on changed YAML files.

This will help with keeping files formatted nicely, with a valid syntax and ensures they are YAML 1.2 compatible.

This PR is separated into 2 commits to make reviewing easier. One adding it, the second correcting existing YAML files.

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

Example entry for configuration.yaml:

# Example configuration.yaml

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

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 homeassistant tests)
• Tests have been added to verify that the new code works.

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

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

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

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

[frenck]

So the PR fails the tests (which I kinda expected to happen).

Questions now:
- Should yamllint part of the test requirements? Or just for pre-commit/ci?!

Added the requirements, also bumped it, realized I used an older version.

[MartinHjelmare]

I like it! Everything that takes the guess work out of code review and formatting without significant pace impact is good.

[MartinHjelmare]

Great!