Emoji reactions for tasks, objectives and key results
### Release notes
You can now contribute to tasks, objectives and key results with the addition of [Award Emojis](https://docs.gitlab.com/ee/user/award_emojis.html#award-emojis) for work items. Before this release, you could only use award emojis on issues, merge requests, snippets and epics.

## Problem
You can't add emoji awards to work items.
## Proposal
Provide a mechanism to add award emojis to work items.
## Acceptance
* [ ] Add emoji award (including custom emojis)
* [ ] Remove emoji award
* [ ] Save awards
* [ ] Redis counter
* [ ] Emoji awards update in real-time
## Redis Counter
* **name:** `users_adding_emoji_award_to_work_item`
* **category:** `work_items`
* **redis_slot:** `users`
* **include in the following aggregation counters:**
* [x] `xmau_plan`
* [x] `xmau_project_management`
* [ ] `xmau_product_planning`
* [ ] `xmau_certify`
* [x] `users_work_items`
* **documentation:** [Service Ping Implementation](https://docs.gitlab.com/ee/development/service_ping/implement.html), [Redis HLL Counters](https://docs.gitlab.com/ee/development/service_ping/implement.html#redis-hll-counters), [Plan's Redis HLL Schema / Approach](https://gitlab.com/gitlab-org/gitlab/-/issues/346046 "Implement new Redis HLL Counters for Work Items")
epic