Add a flag for moving UdfpsEnroll* from SystemUI to settings.

The added files in this CL are mostly copied from SystemUI. Enabling the flag SETTINGS_SHOW_UDFPS_ENROLL_IN_SETTINGS with this CL, the udfps enrollment icons and progress bar are shown in settings.

Turn this flag on via adb:
adb shell setprop sys.fflag.override.settings_show_udfps_enroll_in_settings true

There are some known issues that will be fixed in the following CLs, including:
- When the finger is down on the screen and the lighting circle on the sensor is shown, the fingerprint icon is not hidden.
- When rotating the screen, fingerprint location is not right.
- Currently the scale factor is hard coded for pixel 7 pro, we should update the scale factor based on the device, etc.

Test: manually tested on device
Bug: 260617060
Change-Id: I5aede070eb1de9eb3b5e1400d6e51a8523079852

res/layout/udfps_enroll_enrolling.xml

@@ -39,6 +39,7 @@
             android:orientation="vertical">
 
           <FrameLayout
+              android:id="@+id/layout_container"
               android:layout_width="match_parent"
               android:layout_height="wrap_content"
               android:clipChildren="false"

res/layout/udfps_enroll_view.xml

@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2021 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<com.android.settings.biometrics.fingerprint.UdfpsEnrollView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/udfps_animation_view"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <!-- The layout height/width are placeholders, which will be overwritten by
+         FingerprintSensorPropertiesInternal. -->
+    <View
+        android:id="@+id/udfps_enroll_accessibility_view"
+        android:layout_gravity="center"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:contentDescription="@string/accessibility_fingerprint_label"/>
+
+    <ImageView
+        android:id="@+id/udfps_enroll_animation_fp_progress_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"/>
+
+    <!-- Fingerprint -->
+    <ImageView
+        android:id="@+id/udfps_enroll_animation_fp_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"/>
+</com.android.settings.biometrics.fingerprint.UdfpsEnrollView>