Allow for user to add technical debt to individual violations

[Sebastiaan127001]

For instance, when there are unmerged branches and the team promised to fix it in two weeks, it would be useful to add technical debt to a specific branch. This can only be done for metrics with violations that can be isolated and identified.

[fniessink]

Rename the status "Resolve as fixed" to "Resolve as will be fixed" and change the description from "This [entity] has been fixed and will disappear shortly" to "This will be fixed and should disappear shortly."

Add an end date attribute to the entity that can be entered regardless of what the entity status is. Label: "[Entity] status end date". Help popup: "Consider the status of this entity to be "Unconfirmed" after the selected date."

The measurement entities get an extra attribute "status_end_date", e.g.:

{
  "entity_user_data": {
      "AXellfukmoRlpKCRHShW": {
          "status": "fixed",
          "status_end_date": "2022-02-28T00:00"
      }
  }
}

To update the status and measurement value of the metric we use the same mechanism as used for technical debt end date. Change this function in components/server/src/shared/model/source.py:

    def _entities_to_ignore(self) -> Sequence[dict[str, str]]:
        """Return the entities to ignore."""
        statuses_to_ignore = ("fixed", "false_positive", "wont_fix")
        user_data = self.get("entity_user_data", {})
        entities = self.get("entities", [])
        return [entity for entity in entities if user_data.get(entity["key"], {}).get("status") in statuses_to_ignore]

to also look at the status_end_date.