[Audiosharing] Add audio sharing dialog.

Open the dialog when audio sharing main switch on.

Flagged with enable_le_audio_sharing

Bug: 305620450
Test: Manual
Change-Id: I5b7cf655782a1da8b4fbd42eca11b473bac339b0

src/com/android/settings/connecteddevice/audiosharing/AudioSharingDashboardFragment.java

@@ -75,6 +75,8 @@ public class AudioSharingDashboardFragment extends DashboardFragment {
         mMainSwitchBar = activity.getSwitchBar();
         mMainSwitchBar.setTitle(getText(R.string.audio_sharing_switch_title));
         mSwitchBarController = new AudioSharingSwitchBarController(activity, mMainSwitchBar);
+        mSwitchBarController.init(this);
+        getSettingsLifecycle().addObserver(mSwitchBarController);
         mMainSwitchBar.show();
     }
 }