Implement the function to kill conflicting operations for the intent registry system. This function will return a future which contains an IntentToken once all conflicting operations have been drained (when the opCtx is killed the token should unregister as the thread dies off).

Once this function has been entered no new conflicting operations will be allowed to be registered until that Token has been released

The implementation does not have to be a token specifically but can just be a Future<bool> and a field flag in the intent registry

See this code for how to kill opCtx's

We should take special care to avoid race conditions between registering an intent and killing all active intents