Add dedicated add-on config folder

[mdegat01]

Proposed change

Add a public config folder per addon. This way addons can make internal files for config, dbs, logs, etc. available to users but still have them backed up with the addon (unlike when these files are put into /share or /config today).

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: Document new addon config folder options developers.home-assistant#1960
• Link to cli 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 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

[agners]

While the naming is mostly exposed to developers, I think we should be careful not mixing too many names for this feature and be as explicit as possible.

Public can be a bit misleading as it is still local only (not shared or similar), so I think I'd not use that term.

Suggestion: Generally, I'd suggest to use "add-on config folder" as term for this feature (as opposed to config folder, or Home Assistant config folder).

Since mappings are typically one per line in the conifg, length is not really an issue here. So I rather opt for verbose naming.

For the mapping names, I'd go for:

• config (already exists): Will eventually be the deprecated config for the Home Assistant config folder
• homeassistant_config: New mapping for the Home Assistant config folder
• addon_config: New mapping in case the add-on wishes to have such a new add-on config folder.
• all_addon_configs: New mapping in case the add-on wishes to have the add-on config folder of all the add-ons mapped.