Add "Previously connected devices" activity in settings for system ui QS bluetooth dialog.

Test: adb shell "am start -n 'com.android.settings/.Settings\$PreviouslyConnectedDeviceActivity'"
Bug: 298124674
Change-Id: I388aab93d4952ebc8fbd515be624f336cb083a91
diff --git a/src/com/android/settings/Settings.java b/src/com/android/settings/Settings.java
index ab55bec..7ea4be4 100644
--- a/src/com/android/settings/Settings.java
+++ b/src/com/android/settings/Settings.java
@@ -514,4 +514,6 @@
      * Activity for OneHandedSettings
      */
     public static class OneHandedSettingsActivity extends SettingsActivity { /* empty */ }
+
+    public static class PreviouslyConnectedDeviceActivity extends SettingsActivity { /* empty */ }
 }