bluez5: add parameter to use A2DP source as input

src/daemon/media-session.d/bluez-monitor.conf

@@ -84,6 +84,11 @@ rules = [
                 #channelmix.normalize = false
                 #channelmix.mix-lfe   = false
                 #session.suspend-timeout-seconds = 5      # 0 disables suspend
+
+                # A2DP source role, "input" or "playback"
+                # Defaults to "playback", playing stream to speakers
+                # Set to "input" to use as an input for apps
+                #bluez5.a2dp-source-role = input
             }
         }
     }