Allow execution of client-side code in Shortcuts

[probert94]

Describe your motivation

In an application I am working on I have some actions that can trigger a download or open the file-chooser to upload a file.
The actions are usually displayed as buttons and trigger on click. Now I would like to add Shortcuts for those actions as well.
Right now I have to add a normal ShortcutListener and on the server-side call Button#clickInClient and it seems to work at least in Chromium and Firefox on Windows. But a while back I had problems, especially with Firefox, when opening the file-chooser using executeJs and with the popup-blocker when triggering a download from the server.
Regarding the documentation of showOpenFilePicker it requres transient user activation which might not be the case when calling it after a roundtrip.
Also the popup-blocker in case of a download seems to depend on timing as a server-side breakpoint during the roundtrip seems to trigger it even in Google Chrome.
So therefor I am a bit afraid, that the current solution might not be very stable.
Also the Shortcut executes an unneccessary roundtrip, as the server only calls a client-side function.

Describe the solution you'd like

Therefor I would like to be able to add client-side code to the Shortcutlistener, similar to what resetFocusOnActiveElement already does.
In theory everything that is required should be there already, as Shortcuts use DomListenerRegistration#setFilter under the hood which has access to element and event. So an API to add something to that filter would be enough.

Describe alternatives you've considered

Right now I am using Button#clickInClient with the mentioned drawbacks.
As the Shortcuts-API does not allow to add custom code to the filter the only other alternative I could think of is to create my own Shortcuts implementation based on DomListener.