Use string resources for avatar picker button labels.

This replaces string literals with string resources used
for the avatar picker button labels.

Bug: 222333418
Test: build, flash, and view avatar picker
Change-Id: I6d325d1de215eaa4c47e6a0c0454ae75e147b0ae

packages/SettingsLib/res/values/strings.xml

@@ -1293,6 +1293,8 @@
     <string name="cancel">Cancel</string>
     <!-- Button label for generic OK action [CHAR LIMIT=20] -->
     <string name="okay">OK</string>
+    <!-- Button label for generic Done action, to be pressed when an action has been completed [CHAR LIMIT=20] -->
+    <string name="done">Done</string>
 
     <!-- Label for the settings activity for controlling apps that can schedule alarms [CHAR LIMIT=30] -->
     <string name="alarms_and_reminders_label">Alarms and reminders</string>

packages/SettingsLib/src/com/android/settingslib/users/AvatarPickerActivity.java

@@ -106,13 +106,13 @@ public class AvatarPickerActivity extends Activity {
 
         FooterButton secondaryButton =
                 new FooterButton.Builder(this)
-                        .setText("Cancel")
+                        .setText(getString(android.R.string.cancel))
                         .setListener(view -> cancel())
                         .build();
 
         mDoneButton =
                 new FooterButton.Builder(this)
-                        .setText("Done")
+                        .setText(getString(R.string.done))
                         .setListener(view -> mAdapter.returnSelectionResult())
                         .build();
         mDoneButton.setEnabled(false);