Use IID + full path for Tasks

Problem

the reason for different behaviour is the same that we had for assignees and labels - the root path for the work item is not equal the path in the URL. I fixed this behaviour for assignees and labels in a hacky way - by fetching project path within the work item itself. Should we go the same path for description too or should we prioritize changing the URL to project-relative one? Slack thread

Additional context -- gitlab-design#1514 (comment 1052454929)

Proposal

Use the project's IID and full path for tasks instead of the ID.