[Feature] Issue reporting button

[AsterAether]

Add a button to the mod page, where users can report bugs, preferably redirecting / integrating with github issues

[nihaals]

For just issue tracking I think trying to reinvent GitHub Issues would be unnecessary, especially considering most mods are already on GitHub, or GitLab. For future features that would integrate with the issue log, creating a GitHub app might be better. If we do just provide a link to their issue tracker, following the trend of other attributes this would probably make sense to be in manifest v2. This also matches PyPI.

[MythicManiac]

The comment section probably takes care of this to some extent. A good thing to keep in mind is that most users probably won't have a github account, so just relying on github issues for user feedback might not be a good idea.