[FIX] web: not possible to show a notification via client action

Before this commit, it was not possible to show a message using a client
action. (e.g. show a success message only with core in Python)

Now, it's possible using a client action. This client action call
displayNotification and so we can use the same options also.

A test is added to be sure that this action do not change the current action

Note: in the future a custom registry may be created in a refactoring
to specific function action registry.