Add speaker volume and speaker mute support

[wangfu91]

Tested on my LG 28MQ780.

[dzid26]

Would be good to synchronize with the Windows master volume or better with the specific device volume.

[qkw24]

Hi folks! Can we get some traction on this pull request? I really want the capability to adjust monitor speaker volume and mute support.

[Muhammed-Zaffar]

I really like this idea but I feel like we're trying to add extra functionality with little return in benefit. The ability to control volume for an audio output device is already possible in the taskbar. Functionality like controlling the volume of individual applications and making different audio outputs play sound from different applications (e.g. Discord playing through headphones, Spotify playing through speakers) is already possible with other apps such as Ear Trumpet.