Move build/android directory to root of project (#11283)

android/build.gradle

@@ -0,0 +1,35 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+
+project.ext.set("versionMajor", 5)      // Version Major
+project.ext.set("versionMinor", 4)      // Version Minor
+project.ext.set("versionPatch", 0)      // Version Patch
+project.ext.set("versionExtra", "") // Version Extra
+project.ext.set("versionCode", 34)      // Android Version Code
+// NOTE: +2 after each release!
+// +1 for ARM and +1 for ARM64 APK's, because
+// each APK must have a larger `versionCode` than the previous
+
+buildscript {
+	repositories {
+		google()
+		jcenter()
+	}
+	dependencies {
+		classpath 'com.android.tools.build:gradle:4.1.1'
+		classpath 'de.undercouch:gradle-download-task:4.1.1'
+		// NOTE: Do not place your application dependencies here; they belong
+		// in the individual module build.gradle files
+	}
+}
+
+allprojects {
+	repositories {
+		google()
+		jcenter()
+	}
+}
+
+task clean(type: Delete) {
+	delete rootProject.buildDir
+	delete 'native/deps'
+}