Mark certain plugins as unsupported on mobile

[personalizedrefrigerator]

Mark certain plugins as unsupported on mobile

[personalizedrefrigerator]

The existing manifestOverrides file could be used to add "platforms": ["desktop"] to some of the more popular plugins that only support desktop. Ideally, however, if a plugin author later adds "platforms": ["desktop","mobile"] to the manifest of a plugin that previously was desktop-only, it would be marked as compatible with mobile.

Here are a few options:

1. Add a manifestDefaults.json or similar file that provides default manifest values for different plugins.
2. Add plugin platforms to manifestOverrides.json and instruct plugin authors to open a pull request on the plugins repository when a plugin adds mobile support.
   • A sample diff for this can be found here: https://github.com/joplin/plugins/compare/master...personalizedrefrigerator:joplin-plugin-repo-fork:pr/mark-incompatible-plugins?expand=1
3. Make all plugins last published earlier than some date default to desktop-only, make newer plugins default to supporting both desktop and mobile.

Option 2 should be easiest to implement.