feat: upgrade intrumented tests

    - migrate Java tests to Kotlin
    - replace testutils dependency with the published com.mparticle.internal:mocking library
    - update Mock Server usage for new API

Author: willpassidomo

android-core/src/androidTest/AndroidManifest.xml

@@ -14,7 +14,7 @@
     <application
         android:usesCleartextTraffic="true">
 
-        <activity android:exported="true" android:name=".WebViewActivity">
+        <activity android:exported="true" android:name=".internal.MParticleJSInterfaceITest$WebViewActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />