[LeAudio Broadcast] Shows the broadcast icon on output switcher

When the devcie is broadcasting, the output switcher UI shows the
broadcast icon in the top right corner.
Figma: https://www.figma.com/file/3Kf9EnVdbvQKP5Q1CUviTY/LE-Audio?node-id=0%3A1
Screenshot1: show broadcasting icon
https://hsv.googleplex.com/4875202925166592?node=10
Screenshot2: hide broadcasting icon
https://hsv.googleplex.com/6429825930625024?node=7
Bug: 215469904
Test:
[pass] atest MediaOutputDialogTest
[pass] atest MediaOutputBaseDialogTest

Change-Id: I764f2b0de0d2e008a05b95135507f51ede0b2131