Previously, this would include the entire User record in the update
hash, which was rendered in the response using `to_json`, erroneously
exposing every attribute of that record, including their (now removed)
private token.
Now we only include the user ID, and perform the lookup on-demand.
- Use issue/merge_request IID instead of ID
- Duplicate the original `TimeTrackingEndpoints` concern (+ specs) for V3, since
this is a breaking change.
New endpoints are:
POST :project_id/(issues|merge_requests)/(:issue_id|:merge_request_id)/time_estimate"
POST :project_id/(issues|merge_requests)/(:issue_id|:merge_request_id)/reset_time_estimate"
POST :project_id/(issues|merge_requests)/(:issue_id|:merge_request_id)/add_spent_time"
POST :project_id/(issues|merge_requests)/(:issue_id|:merge_request_id)/reset_spent_time"
GET :project_id/(issues|merge_requests)/(:issue_id|:merge_request_id)/time_stats"
