Add GameViewControl for Themes

[cnapolit]

Currently, Playnite Sounds is unable to behave as needed, such as muting when videos are playing audio. Providing a View themes could load to control Music in place of the plugin would provide a more cohesive experience.

ExtraMetaDataLoader already does something very similar: https://github.com/darklinkpower/PlayniteExtensionsCollection/blob/master/source/Generic/ExtraMetadataLoader/ExtraMetadataLoader.cs#L102