Extend per table metrics with some RPC layer measures

RPC metrics are whole server in scope. We should extend the per-table metrics to also track a subset of RPC metrics on a per table basis. This would give better insight into the subjective experience of each use case. 

Consider TotalCallTime, ProcessCallTime, QueueCallTime. Table metrics already track request counts and server side processing latencies, just not queueing effects at the RPC layer.

Ideally we avoid introducing another configuration option but this could be made optional, if overheads are significant (measure them)