Permit Firebase analytics to be disabled

Set up configuration parameters so that analytics can be completely disabled based on the flavor being built

android/ScratchJr/app/build.gradle

@@ -6,6 +6,7 @@ android {
 
     defaultConfig {
         applicationId "org.scratchjr.android"
+        manifestPlaceholders = [disableAnalytics: "false"]
     }
 
     buildTypes {
@@ -24,6 +25,7 @@ android {
             targetSdkVersion 29
             versionCode 22
             versionName "1.2.11"
+            manifestPlaceholders = [disableAnalytics: "true"]
         }
     }
 

android/ScratchJr/app/src/main/AndroidManifest.xml

@@ -18,6 +18,9 @@
         android:theme="@style/AppTheme"
         android:hardwareAccelerated="true"
         android:resizeableActivity="false">
+
+        <meta-data android:name="firebase_analytics_collection_deactivated" android:value="${disableAnalytics}" />
+
         <provider android:name="ShareContentProvider"
                   android:grantUriPermissions="true"
                   android:authorities="${applicationId}.ShareContentProvider">