Support Force Touch to Preview items

[mikekazakov]

(migrating existing issues/tasks from the previously used internal issue tracker)
Finder checks for the force level to decide whether a click should show a floating preview panel. NC can do the same.
See:
https://developer.apple.com/documentation/appkit/nsresponder/1534071-pressurechangewithevent?language=objc
https://developer.apple.com/documentation/appkit/nsevent#1651718