specify android namespace (#82)

Author: JulianBissekkou

arcgis_map_sdk_android/android/build.gradle

@@ -31,6 +31,12 @@ apply plugin: 'kotlin-android'
 android {
     compileSdkVersion 31
 
+
+    // Conditional for compatibility with AGP <4.2.
+    if (project.android.hasProperty("namespace")) {
+        namespace 'dev.fluttercommunity.arcgis_map_sdk_android'
+    }
+
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_11
         targetCompatibility JavaVersion.VERSION_11