Change PreferenceController#getSummary return type.

Return CharSequence instead of String.

All user visible string should be modeled as CharSequence.

Bug: 73950519
Test: robotest
Change-Id: I30befef0c33f94351d4a2774e283bd1ed804aa8b

src/com/android/settings/bluetooth/BluetoothDeviceNamePreferenceController.java

@@ -113,7 +113,7 @@ public class BluetoothDeviceNamePreferenceController extends BasePreferenceContr
     }
 
     @Override
-    public String getSummary() {
+    public CharSequence getSummary() {
         String deviceName = getDeviceName();
         if (TextUtils.isEmpty(deviceName)) {
             return super.getSummary();

src/com/android/settings/bluetooth/BluetoothDeviceRenamePreferenceController.java

@@ -72,7 +72,7 @@ public class BluetoothDeviceRenamePreferenceController extends
     }
 
     @Override
-    public String getSummary() {
+    public CharSequence getSummary() {
         return getDeviceName();
     }