Undo/redo shortcuts don't work on Cyrillic keyboard layout

[nikku]

Describe the Bug

Some users (i.e. using German keyboard layout) expect actual keys to trigger certain features. Other users (i.e. Cyrillic keyboard layouts) expect positional shortcuts to trigger an action.

We currently do not properly handle positional keyboard shortcuts for undo/redo, giving users the impression that it does not work.

Steps to Reproduce

1. Open [https://demo.bpmn.io/s/start]
2. Model a change
3. Press CTRL/CMD + Z (positional) on a Cyrillic keyboard layout
4. See nothing happening

Expected Behavior

We properly handle both positional and literal key presses.

Environment

• Browser: Any
• OS: Linux/Any
• Library version: v17.0.0

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Related to #1888
Related to camunda/camunda-modeler#2724