Add hint to EditText for Talkback

Set the title as the hint of EditText to fix the missing accessibility
label.

Fix: 386758099
Test: atest DeviceNamePreferenceControllerTest
Flag: EXEMPT bug fix
Change-Id: Icde6796aa3faa3e0ad79611ba2dd0b18b13590a7

src/com/android/settings/widget/ValidatedEditTextPreference.java

@@ -67,6 +67,9 @@ public class ValidatedEditTextPreference extends CustomEditTextPreferenceCompat
     protected void onBindDialogView(View view) {
         super.onBindDialogView(view);
         final EditText editText = view.findViewById(android.R.id.edit);
+        if (editText != null) {
+            editText.setHint(getDialogTitle());
+        }
         if (editText != null && !TextUtils.isEmpty(editText.getText())) {
             editText.setSelection(editText.getText().length());
         }