[AGE-365] Add new status for evaluation Queued

[mmabrouk]

Sometimes, evaluations aren't executed because all celery workers are occupied. Users should be informed that their evaluation is queued.

We need to add a new state queued, and modify the backend code to determine this state from celery. We need also to handle this state correctly in frontend

_{From SyncLinear.com | AGE-365}

[jp-agenta]

@mmabrouk This should be (solved and) closed, right ?

[mmabrouk]

yep