Add --songuri and --listuri to enable playing a song or playlist Uri

[Myoldmopar]

Addresses:

• Fixes Play Playlist URI - feature request  #5
• Potentially the start of addressing play a song you request #15 by combining with some other service to get URI by artist/track and such, but that may be a stretch

With these new arguments, the user can provide a song or playlist URI to the CLI and it should play it. The URI can be found by "sharing" a track from the Spotify app. The URL will look like:

https://open.spotify.com/track/0z5KIZSt0Vcm8diVg0WBjP?si=16c79071b0134c83
                               ^^^^^^^^^^^^^^^^^^^^^^
                                ^ Spotify URI Here ^

Maybe there's an easier way? Anyway you can call it from the CLI like:

spotifycli --songuri 0z5KIZSt0Vcm8diVg0WBjP

or

spotifycli --listuri 37i9dQZF1DZ06evO0jO79m

And it plays just fine. I'm totally open to adjusting the naming of the command line arguments as you prefer.

Note, this will have minor conflicts with if #85 is merged. I'm happy to resolve them, just tell me what method you prefer for the squash/merge/rebase whatever and I can do it.

[Myoldmopar]

Code walkthrough completed. Looking forward to hearing your thoughts!

[pwittchen]

Thanks for the PR! Looks good.