Dream settings refactor.

We will be re-using the grid UI for the dream complication picker, so
this change refactors some of that logic so it can be re-used in the
complication controller.

We also update some of the UI here to match the most recent UX
decisions.

http://screen/BxhAwZwQSVoxUmN.png

Test: locally on device
Test: make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.dream.DreamPickerControllerTest"
Bug: 214250590
Bug: 215703483
Change-Id: I9fbfa0f0cd31ae3d119c7cd1a9562d4cdb203d6c

res/drawable/ic_dream_check_circle.xml

@@ -0,0 +1,24 @@
+<!--
+Copyright (C) 2022 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.
+-->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="@dimen/dream_item_icon_size"
+        android:height="@dimen/dream_item_icon_size"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M12.0,2.0C6.48,2.0 2.0,6.48 2.0,12.0s4.48,10.0 10.0,10.0 10.0,-4.48 10.0,-10.0S17.52,2.0 12.0,2.0zm-2.0,15.0l-5.0,-5.0 1.41,-1.41L10.0,14.17l7.59,-7.59L19.0,8.0l-9.0,9.0z"/>
+</vector>