Updated android build files to new asset/shader folder structure

Make use of global gradle variables
Updated gradle

android/build.gradle

@@ -1,4 +1,10 @@
-// Top-level build file where you can add configuration options common to all sub-projects/modules.
+/**
+ * Copyright (C) 2016-2023 by Sascha Willems - www.saschawillems.de
+ *
+ * This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
+ */
+
+/** Top-level build file where you can add configuration options common to all sub-projects/modules */
 
 buildscript {
     repositories {
@@ -6,7 +12,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.2.0'
+        classpath 'com.android.tools.build:gradle:7.0.0'
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
     }
@@ -17,4 +23,12 @@ allprojects {
         google()
         jcenter()
     }
+}
+
+ext {
+    minSdkVersion = 19
+    targetSdkVersion = 26
+    compileSdkVersion = 26
+    shaderPath = '../../../shaders/'
+    assetPath = '../../../assets/'
 }