example: add media control play/pause example

[aymanbagabas]

This simply adds a new examples module with a play/pause example using
the newly added media control api bindings. This example simply prints the current artist and song from the current active session, the session status, then toggles play/pause.

Needs: #109

Output:

PS C:\Users\Ayman\Source\saltosystems\winrt-go\examples> go run .\playpause\
Now playing: Volkovitsh - Sunset Drive - house mix n°8
Current playback status before toggle: Playing