feat(android): Load Android Gradle Plugin conditionally (#2623)

android/build.gradle

@@ -3,13 +3,19 @@ def safeExtGet(prop, fallback) {
 }
 
 buildscript {
-  repositories {
-    google()
-    jcenter()
-  }
+  // The Android Gradle plugin is only required when opening the android folder stand-alone.
+  // This avoids unnecessary downloads and potential conflicts when the library is included as a
+  // module dependency in an application project.
+  if (project == rootProject) {
+    repositories {
+      google()
+      jcenter()
+    }
 
-  dependencies {
-    classpath 'com.android.tools.build:gradle:3.5.2'
+    dependencies {
+      //noinspection GradleDependency
+      classpath("com.android.tools.build:gradle:3.5.2")
+    }
   }
 }