Quotas for feedback is LAST date instead of FIRST

[scottmcdonnell]

Context

Studio name: JAM Media
Zou version: 0.20.18
Zou installation type: self-hosted docker

Describe the bug
Quotas for feedback date states that it is the FIRST recorded feedback date. If you have a feedback status of, for example, "FOR REVIEW" and the entity goes to this status multiple times the end_date in the database table tasks is updated each time making the end_date equal to the LAST recorded feedback date instead of the first.

This is very problematic for stats, as stats should be recorded once only and be immutable.

Expected behavior
the first feedback date should be updated once only. I would suggest that end_date is not the appropriate field for this as it is used for time spend measurements. better would be first_feedback_date.

in tasks_service.is_finished() the check for feedback request has no check for a previous value for end_date therefore end_date is updated.

similarly real_start_date and done_date are also updated. it would be great to also have a first_wip_date and first_done_date

Screenshots

Additional context
Add any other context about the problem here.