Add Lit analyzer

[bramkragten]

This PR adds ts-lit-plugin and lit-analyzer.
If you have the vs code lit-plugin installed, it will give you type checking, autocomplete and checks of lit HTML templates.

You can also run yarn run lint:lit to get a list of all the issues (a lot right now)

We don't enforce these rules now, but by making them visible we hope we can work towards enforcing them in the future by fixing things step by step.

Type of change

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

Example configuration

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.
• There is no commented out code in this PR.
• 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