Enable installation via HACS

[ghjklw]

Enable installation via HACS to make the process significantly easier and to enable easy updates and uninstall.

Changes

• Reorganize the repository to follow the file structure required by HACS.
• Update manifest.json to add all attributes required for integrations.
• Add hacs.json manifest file.
• Add Github actions to automatically validate every commit using HACS actions and Hassfest.
• Update README.md to document installation through HACS.

Other changes to the repository/process required

• To release a new version, the version number should be bumped in manifest.json and a new Github release should be created.
• Github topics should be defined.

Further actions to publish to HACS repository

• Grohe Sense logo should be added to Home Assistant brands repository.
• The brands check in HACS Github action should be re-enabled.
• A PR should be made to add gkreitz/homeassistant-grohe_sense to HACS default integration

Relevant documentation

• HACS general requirements
• HACS integration requirements
• Process to add to HACS default repositories

[ghjklw]

If you accept this PR, I would obviously be happy to help with the next steps to get it added to HACS default repositories!

[seranoo]

👍👍👍

[BenTristem]

Thanks for working on this, I have emailed the repo owner today and hopefully they will start accepting PRs

[pertakman]

I made a pull request today with a suggestion to change from mbar to bar. Also suggested the version change in manifest.json without realizing that it was part of your pull request already.

Have you been able to get hold of Gunnar Kreitz?

[mattjgalloway]

Looks like this repo is probably stale now? I'd love HACS support for this though. Has anyone considered a fork yet and maintain it? I'd be happy to assist.