Promote frequently used devices in new device selection drop-down

I love the new device switching dropdown in this indicator, but I have five output devices and my second most used device doesn't appear in the drop down.

It would be nice if my most frequently used devices rose to the top of this dropdown.

Start at the new device switching dropdown in the sound indicator and trace how output devices are populated and selected. Clarify how device usage should be measured and retained, then verify that frequently used output devices appear first while all available devices remain selectable.

Written by the indexing model from the issue text.