I think this should be self-contained rather than recycling alexa_watch_video_playlist(), like the others are. Since it's a nav command, there shouldn't be a response either (it should return question(' ')).

Why did the German utterance file change so much? I ran the them through the utterance generator to check, and nothing else changed like it did in this PR.

Lastly, we'll need to add at the same time support for audio playlists and a 'generic' phrasing that excludes the playlist type to line up with the other commands (i.e., open playlist foo). This needs to happen simultaneously to ensure there aren't collisions with each other or the other Intents that are similar.

We'll need to test for weighting issues as well with shorter open commands (open movies vs open movie playlist, etc), since it's possible Alexa might favor these new commands much more due to the slots involved, which equates to more sample phrases.

If we add much more for open here, we might also want to consider removing open as an invocation word for AddonExecute.

Superseded by #207 which includes what I talked about above.