check if event handler has parameters without default value

[falkoschindler]

This PR changes the way event handlers get called with or without event arguments. Consider this example:

ui.button('1', on_click=lambda: ui.notify('1'))
ui.button('2', on_click=lambda _, x=2: ui.notify(x))
ui.button('3', on_click=lambda x=3: ui.notify(x))

In the last case, event arguments have been passed to x because the event handler does expect arguments. With this PR, however, x remains set to 3, because the event handler does not expect any argument without a default value.

I think this is a reasonable distinction, because a parameter with a default value most certainly won't accept event arguments. And it helps in cases like https://stackoverflow.com/q/76348605/3419103 where local variables need to get captured in a lambda statement. Filling those parameters with event arguments confuses many users.