[Wi-Fi DPP] Improve TalkBack information for events

Title and summary may be changed after user operations or Wi-Fi Easy connect handshake,
setAccessibilityLiveRegion could specify accessibility services to announce these changes.

In WifiDppAddDeviceFragment, I set title before summary for correct TalkBack announce sequence.

Bug: 137069941
Test: manual
Change-Id: Id032cfcb86c350feeac808f070665ac26261ceb8

src/com/android/settings/wifi/dpp/WifiDppQrCodeBaseFragment.java

@@ -72,6 +72,9 @@ public abstract class WifiDppQrCodeBaseFragment extends InstrumentedFragment {
                     .build();
             mGlifLayout.getMixin(FooterBarMixin.class).setPrimaryButton(mRightButton);
         }
+
+        mGlifLayout.getHeaderTextView().setAccessibilityLiveRegion(
+                View.ACCESSIBILITY_LIVE_REGION_POLITE);
     }
 
     protected void setHeaderIconImageResource(@DrawableRes int iconResId) {