Key bindings on diagram tools can conflict with browser actions

[pcdavid]

#1626 added the capability to configure a key binding to invoke a tool on a diagram.
When using a key binding like Ctrl-d (or Ctrl-f, or others) which is already used by the browser, we correctly invoke our diagram tool, but we do not prevent the default browser operation to also be triggered.

See #6492 for more context.