Rename RadioButtonPreference to SelectorWithWidgetPreference, and add a checkbox styling option.

This rename makes it slightly less confusing to have both radio and checkbox display options. Functionally, this preference was already equivalent to a checkbox (with checking/unchecking functionality managed by the caller); the reason to use this class for settings checkboxes rather than the base CheckBoxPreference is for the added widget functionality.

This change leaves RadioButtonPreference as-is to make it easier to bring google3 uses in without having to be in lockstep, but RadioButtonPreference will be deleted in a future CL.

Test: SelectorWithWidgetPreferenceTest, RunSettingsLibRoboTests
Bug: 190180868

Change-Id: I0811997b4625f1292b1842ea353a90221159bb50
diff --git a/packages/SettingsLib/SelectorWithWidgetPreference/AndroidManifest.xml b/packages/SettingsLib/SelectorWithWidgetPreference/AndroidManifest.xml
new file mode 100644
index 0000000..51fc7ed
--- /dev/null
+++ b/packages/SettingsLib/SelectorWithWidgetPreference/AndroidManifest.xml
@@ -0,0 +1,23 @@
+<?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.
+-->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.android.settingslib.widget">
+
+    <uses-sdk android:minSdkVersion="21" />
+
+</manifest>