Modified sound@cinnamon.org to autoexpand "Output device" category.

[SpeeQz1]

The Linux Mint sound@cinnamon.org applet doesn't display the system's output devices by default when a user right clicks on the applet to open the context menu.

This change modifies it so that the category Output device is already expanded and doesn't hide what audio devices the user's system has which should make their discovery easier.

[claudiux]

This should be an option (which already exists in the Enhanced Sound applet).

[SpeeQz1]

@claudiux Implemented toggleable options, for both Applications and Output device.

Output device is expanded by default and Applications is not.