Display completed checklist information in merge request description
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=545634)
</details>
<!--IssueSummary end-->
## Proposal
Display completed checklist information from merge request description.
1. Shows total count
2. Shows completed count
3. Excludes items strikethrough from count
4. Adds a `•` to separate the count from the edited information
Behavior is similar to issue descriptions.
## Screenshot

issue