[LE broadcast sink] Add the source list in boradcast sink UI.

Add the source list in boradcast sink UI.
Add the password dialog.

hsv link1: https://hsv.googleplex.com/6256032201310208
hsv link2: https://hsv.googleplex.com/5934966820044800
hsv link3: https://hsv.googleplex.com/6238095344140288
Bug: 228258236
Test: manual test

Change-Id: I698c2f7aba9baa9f143a98629b8796eda57fb379