add 'play queue' feature

[KiaraGrouwstra]

currently, in my experience the queue does not seem to auto-play queued items, instead still relying on the user to manually run (p / Enter) a podcast episode when the previous is done.
i think common media players like VLC additionally support booting with not a single file/uri as its argument, but would support multiple as well.
it would be cool to add an additional keybind to play all the (queued) podcast episodes.

[gilcu3]

That certainly makes sense, although my plan is to implement the play capability on the app itself, to avoid depending on external apps. Therefore, I will probably not implement this for the moment, but I am open for PRs if anyone wants to step in.