[themes] Show extension info in Preferences: Color Theme panel

<!-- Please search existing issues to avoid creating duplicates. --> In current `Preferences: Color Theme` panel, there is no extension info that lets users know which extension provided the themes. I'd like to purge some unwanted theme extensions, but I don't know which one I should uninstall.  It will be great if we can add the extension info at the right of theme name :) Something like the below picture.  <!-- Describe the feature you'd like. -->