Initial migration of the store to be sync (#10592)

* Migrating audit store

* Final migration example for the audit store

* async example

* Ending migration

* Removing Async helper

* Fixing tests

* Fixing govet problems with the StoreResult instanstiation

cmd/mattermost/commands/userargs.go

@@ -30,9 +30,7 @@ func getUserFromUserArg(a *app.App, userArg string) *model.User {
 	}
 
 	if user == nil {
-		if result := <-a.Srv.Store.User().Get(userArg); result.Err == nil {
-			user = result.Data.(*model.User)
-		}
+		user, _ = a.Srv.Store.User().Get(userArg)
 	}
 
 	return user