Initialize AssignForwardingHandler and KeyStoreHandler

Initializes the AssignForwardingHandler, aswell as the KeyStoreHandler correctly. Additionally key store Add and Delete methods have been extended to use the internal EventBus.

We should also remove all unnecessary parameter forwarding of an eventBus and use the NewEventBus approach, introduced in this MR.

goKMS/gnmiHandlers/kms/keyStoreHandler.go

@@ -42,7 +42,9 @@ func (yh *KeyStoreHandler) Init(config *handler.Config, publishToSubsFunc func([
 		return err
 	}
 
-	yh.updateOrCreateKeyStores()
+	if _, err := yh.updateOrCreateKeyStores(); err != nil {
+		return err
+	}
 
 	// Start the go routine that takes care of any update from the kms
 	go func() {