Immediately send query run results

[seanlinsley]

Query runs are submitted as part of activity snapshots every 10 seconds, but that creates an unnecessary latency. This PR improves that by adding a new snapshot type which is submitted immediately once a query run is complete.

Note that we'll want to continue submitting query runs as part of activity snapshots so that:

• long-running queries are reported as running before they're complete
• the result is still received if network issues caused the query run snapshot to be lost (activity snapshots repeatedly submit query runs for 10 minutes after they're complete, to be sure we receive the result)