Add support for querying latest ingested event timestamp

Add support for querying latest ingested event raw timestamp.
Useful for the knowing how much updated information realtime pipeline has specifically with high rollup granularity.
Spoke with FJ and we thought that the maxIngestedEventTime would make more sense as part of a new IngestMetadataQuery rather than TimeBoundary (since it's about metadata, not data). Let us know if you want to discuss that or if you have thoughts.