Add support for TSUID queries to Query and TsdbQuery. It is fully backwards
compatible. If a list of tsuids is provided, the metric/tags are ignored.
Otherwise the query behaves as usual. A row key regex is built to return only
the rows matching the TSUID. All TSUIDs in the list must share the same metric
and their data will be aggregated together.
Modify TSSubQuery to use a generic List for TSUIDs
Modify TSQuery to supply the list of TSUIDs to a TsdbQuery if given
Update QueryRpc to accept TSUID queries