Describe the Bug

The problem relates to detecting key events, particularly when relying on the event.key property, which returns different values depending on the active keyboard layout. We should fix it in https://github.com/bpmn-io/diagram-js/blob/develop/lib/features/keyboard/KeyboardUtil.js by relying on event.code === 'KeyC' instead for example I believe

Steps to Reproduce

1. Set your keyboard layout to Ukrainian.
2. Try to copy/paste elements with the Ctrl+c/Ctrl+v