[FEAT] File drag and drop support

[Pastitas]

Is this a new feature request?

• [X] I have searched the existing issues

Wanted change

Add an togglable option to make the app upload automatically any files that are dragged and dropped there in the main page (maybe using some default upload folder setting) .

If this could somehow be integrated with the vnc host to drag the same file to the used application inside would be amazing but that seems way more complex, maybe that could be a future improvement

Reason for change

Right now there's no action associated with dragging and dropping files on kasmvnc webpage, instead the default action by the browser is done. Also in the settings menu there's an option for file upload that, when that specific window is open, allows for file uploads via drag and drop.

This makes sense for applications in which you'd normally want to drag and drop a file into, like https://github.com/linuxserver/docker-orcaslicer

Proposed code change

No response