Harden SQL journal and snapshot store against initialization failures (#444)

Port of akkadotnet/akka.net#7325

Author: Aaronontheweb

src/Akka.Persistence.Sql/Journal/SqlWriteJournal.cs

@@ -134,9 +134,8 @@ private bool Initializing(object message)
 
                 case Status.Failure fail:
                     _log.Error(fail.Cause, "Failure during {0} initialization.", Self);
-                    Context.Stop(Self);
-                    return true;
-
+                    // trigger a restart so we have some hope of succeeding in the future even if initialization failed
+                    throw new ApplicationException("Failed to initialize SQL Journal.", fail.Cause);
                 default:
                     Stash.Stash();
                     return true;

src/Akka.Persistence.Sql/Snapshot/SqlSnapshotStore.cs

@@ -62,7 +62,8 @@ private bool WaitingForInitialization(object message)
 
                 case Status.Failure msg:
                     _log.Error(msg.Cause, "Error during {0} initialization", Self);
-                    Context.Stop(Self);
+                    // trigger a restart so we have some hope of succeeding in the future even if initialization failed
+                    throw new ApplicationException("Failed to initialize SQL SnapshotStore.", msg.Cause);
                     return true;
 
                 default: