Add function to call launch of app with contentId

[Bretterteig]

As far as I understood the code there is currently not method of launching the app via luna://system.launcher/launch and the contentId parameter being evaluated.

This would proof valuable to me for integration into e.g. Home Assistant

Youtube and Netflix have similar functionality built-in. Their payload looks like this:
Netflix
{ "id": "netflix", "contentId": "m=http://api.netflix.com/catalog/titles/movies/80145130&source_type=4" }

Youtube
{ "id": "youtube.leanback.v4", "contentId": "v=29reTU13exU" }

Future Jellyfin?
{ "id": "org.jellyfin.webos", "contentId": "id=601e1895b63ef58ba2de9797736eaba2&serverId=e4cae6cfc73b4cd58ad9351aa33de082" }
The above contentId string would allow to select server and media automatically and simply start playing :)