Themes: Add Live previews for applied themes and fonts

Co-authored-by: ender1324 <ender1324@abv.bg>
Signed-off-by: AndroBuddy <anirudhchimpidi8@gmail.com>
Signed-off-by: Hưng Phan <phandinhhungvp2001@gmail.com>

res/drawable/preview_wallpaper.xml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+    Copyright (C) 2020 ProjectFluid
+
+    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="1280dp"
+    android:height="510dp"
+    android:viewportWidth="1280"
+    android:viewportHeight="510">
+    <path
+        android:pathData="M -11 -788 L 1291 -788 L 1291 1156 C 1291 1234.42 1227.42 1298 1149 1298 L 131 1298 C 52.576 1298 -11 1234.42 -11 1156 L -11 -788 Z"
+        android:fillColor="?android:attr/colorAccent"
+	android:fillAlpha="0.2" />
+    <path
+        android:pathData="M 1281 60 L 1227.17 68.203 C 1173.33 76.405 1065.67 92.81 958 158.431 C 850.333 224.051 742.667 260.203 635 252 C 527.333 243.797 419.667 174.836 312 158.431 C 149 133.594 42.833 306.077 -11 355.292 L -11 969 C -11 1043.56 49.42 1104 123.979 1104 L 1146.02 1104 C 1220.58 1104 1281 1043.56 1281 969 L 1281 60 Z"
+        android:fillColor="?android:attr/colorAccent"
+	android:fillAlpha="0.1" />
+</vector>
+