Add compact mode to the Volume Control application

In the Windows sndvol32 there is Ctrl+S hotkey that allows you to switch the mixer into a compact mode.

Being fair: ReactOS does actually have this (compact) "small_master" mode. However, it's only possible to enable it using the "SndVol32.exe -s", so there is not hotkey (pending on implementation) for it to change the "normal_master" mode.

I want to investigate if it is linked with a Registry entry too, Windows change of the mode is recursive/persistent once it's closed, even with the ReactOS one.