Disable other suggestions in discussion when applying
The following discussion from gitlab-ce!28160 should be addressed:
- [ ] @pslaughter started a [discussion](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28160#note_167475697):
> **note:** It's kind of problematic that we handle `isApplying` as internal state to this component:
>
> - Complexity for passing callback in event emitter.
> - Can't disable other suggestion's when applying one.
>
> I'm going to create a follow up issue to address this.
issue