[android] - update gradle and plugin for Android Studio 2.3 stable, update support library to latest version, add dexOptions to increase build times. (#8271)

platform/android/MapboxGLAndroidSDKTestApp/build.gradle

@@ -46,6 +46,12 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+
+    dexOptions {
+        maxProcessCount 8
+        javaMaxHeapSize "2g"
+        preDexLibraries true
+    }
 }
 
 dependencies {