feat: closing task

[maxceem]

ref issue #693

• Button to close the task added to the edit page, but not the list, as confirmed by Vikas No way to close a challenge of type TASK #693 (comment)

  • Close Task button is only showed after the challenge is activated as clarified by Vikas No way to close a challenge of type TASK #693 (comment)

  

• As not all the fields which are needed to close a task are required in the form, I've added an error message which asks user to fill all the fields for closing task:

  

• If all required info is there and user clicks Close Task button, there is a confirmation dialog:

  

• If user clicks Confirm form is being processed and a standard successful message is showing:

  

  Though at the moment when I'm trying to close the task with the assigned member who is added as a winner there is an error. I guess setting task.memberId doesn't add the user to the challenge, because when I send the same request but without winners array it works, and the challenge is marked as completed:

  

[vikasrohit]

LGTM. Will debug the sync issue with legacy challenge processor after merging in dev.