Add issue_tracker integration manifest property

[frenck]

Proposed change

Add the issue_tracker property to the integration manifest.

This allows custom integration to provide links to their issue trackers in the manifest, bringing users directly to the right place to report issues.

This can later be added to the info dev tools, but more importantly, to the error messages dialogs.

Parent PR: home-assistant/core#35153

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: Add issue_tracker property manifest documentation developers.home-assistant#493

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

[frenck]

@bramkragten Backend has been merged.