On new session, user executor executes, and unpause operation repo

* On a new session, we will trigger the user executor to execute any pending requests, in case there is a failed create user request that should be retried. We can't rely on the operation repo flushing to trigger the user executor as it bypasses the operation repo.

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OneSignalUserManagerImpl.swift

@@ -535,7 +535,9 @@ extension OneSignalUserManagerImpl {
             return
         }
         start()
-
+        
+        OSUserExecutor.executePendingRequests()
+        OSOperationRepo.sharedInstance.paused = false
         updateSession(sessionCount: 1, sessionTime: nil, refreshDeviceMetadata: true)
 
         // Fetch the user's data if there is a onesignal_id