Adding support for customizing the trigger button

[schaper1337]

Something analog to what filament provides for table filters trigger button:

Filament's customizing the filters trigger action

This would allow an action to be passed as a closure, with the ability to configure the trigger button in a Filament consistent way.

If this is not desired, it would be cool if the trigger button had the same styling as the notification trigger button that comes with filament's notifications, so it has a cleaner feel.