Make TestActivity exported for firebase-inappmessaging-display (#5185)

Prepare for SDK 33.

Signed-off-by: utzcoz <[email protected]>
Co-authored-by: Rodrigo Lazo <[email protected]>

Author: utzcoz

firebase-inappmessaging-display/src/androidTest/AndroidManifest.xml

@@ -3,7 +3,7 @@
 
   <application>
     <uses-library android:name="android.test.runner"/>
-    <activity android:name=".TestActivity">
+    <activity android:name=".TestActivity" android:exported="true">
       <intent-filter>
         <action android:name="android.intent.action.MAIN"/>
         <category android:name="android.intent.category.LAUNCHER"/>