text: Title: extend non-iid issue check in Datalab
  Body: Currently Datalab's non-iid issue type is only detected based on `features`:
  https://docs.cleanlab.ai/master/cleanlab/datalab/guide/issue_type_description.html#non-iid-issue
  
  If the user does not input `features`, but does provide` pred_probs`, run this same check based on the `pred_probs` instead (just treat them as features). 
  
  Note that if the user did provide `features` or there was already a KNN graph constructed in Datalab, the results should be returned as they currently are, not using the `pred_probs` at all!
  
  Reference:  https://github.com/cleanlab/cleanlab/blob/master/cleanlab/datalab/internal/issue_manager/noniid.py  