[Feature request] Add "or" separator option for keyboard shortcut combos

### Description

Keyboard shortcut combo components currently only support + as a separator (e.g., Ctrl + C). Some keyboard interactions require an or separator to communicate alternative key combinations (e.g., Home **or** Fn + Left Arrow).

### Requested change

Add an option to use **or** (in addition to the existing **+**) when building keyboard shortcut combos.

### Considerations

There's a point where these keyboard shortcut components become over-engineered, and we may already be there. Let's try to implement this in a simple way if possible. As it is, we should simplify what's already implemented, per:
- https://github.com/github/annotation-toolkit/issues/24