Cannot override default key bindings

[JonasHelming]

Bug Description:

It is not possible to override default key bindings, the original command will still be triggered, even if the user assigns the command to another key binding.

Steps to Reproduce:

1. open keybindings and search for "trigger inline completion"
2. Rebind to another key combination
3. open a code editor and observe that the key combination still triggers inline completion (and does not add a special space)

Additional Information

• Operating System:
• Theia Version: 1.57