[SPARK-4537][Streaming] Expand StreamingSource to add more metrics

Add `processingDelay`, `schedulingDelay` and `totalDelay` for the last completed batch. Add `lastReceivedBatchRecords` and `totalReceivedBatchRecords` to the received records counting.
Hi TD, sorry to bother you again, I'm not if there's a better way to address this problem, would you mind giving me some hints, thanks a lot.