Fix outside package target activities not opening

This fix includes any launch URLs set to open the browser or another app

The issue was due to an Activity backstack not being built correctly.
Both `NotificationOpenedReceiver` and the target `Activity` were
launched with `FLAG_ACTIVITY_NEW_TASK` however this means when
`NotificationOpenedReceiver` is finished it does not bring up the target
since it is on a different task. The Android flag `allowTaskReparenting`
allows this to happen, however this can effect the backstack of the main
task which we don't want to do.

Setting `android:taskAffinity` does `FLAG_ACTIVITY_NEW_TASK` and
`allowTaskReparenting` for us. By setting the value to "" (empty string)
it prevents any side effects on existing tasks as it means it has no
affinity to associate it with. This allowed us to clean up some runtime
logic to add `FLAG_ACTIVITY_NEW_TASK` and others we no longer need now.

Author: jkasten2

OneSignalSDK/onesignal/src/main/AndroidManifest.xml

@@ -136,6 +136,7 @@
           android:name="com.onesignal.NotificationOpenedReceiver"
           android:noHistory="true"
           android:excludeFromRecents="true"
+          android:taskAffinity=""
           android:theme="@android:style/Theme.Translucent.NoTitleBar"
           android:exported="true" />
 

OneSignalSDK/onesignal/src/main/java/com/onesignal/GenerateNotificationOpenIntent.kt

@@ -17,19 +17,9 @@ class GenerateNotificationOpenIntent(
     ): Intent {
         // We use SINGLE_TOP and CLEAR_TOP as we don't want more than one OneSignal invisible click
         //   tracking Activity instance around.
-        var intentFlags =
+        val intentFlags =
             Intent.FLAG_ACTIVITY_SINGLE_TOP or
             Intent.FLAG_ACTIVITY_CLEAR_TOP
-        if (!startApp) {
-            // If we don't want the app to launch we put OneSignal's invisible click tracking Activity on it's own task
-            //   so it doesn't resume an existing one once it closes.
-            intentFlags =
-                intentFlags or (
-                    Intent.FLAG_ACTIVITY_NEW_TASK or
-                    Intent.FLAG_ACTIVITY_MULTIPLE_TASK or
-                    Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET
-                )
-        }
 
         return Intent(
             context,