Condition to filter upon checklist status for Issue and/or Merge Request

Summary

Allow filtering upon the checklist status of an issue or a merge request

Proposal

It's possible to determine the checklist status of an issue or merge request via the API:

• https://docs.gitlab.com/ce/api/issues.html#single-issue
• https://docs.gitlab.com/ce/api/merge_requests.html#single-issue

Via the task_completion_status field

Use cases

• Close the open triage package issues where all items have been checked off as completed
• Find triage package issues with outstanding task list items