Consider adding an optional queuing utility for runs on a single connection

[jraymakers]

The default behavior of DuckDB when a statement is run on a connection that has an actively-running statement is to interrupt the active statement. This can be surprising and undesirable in some scenarios. It might be helpful to add a utility that instead queues runs.

It may not be feasible to support this for advanced modes of running, such as streaming and pending results. But it shouldn't be too hard for simple materialized runs. Perhaps a way this could be exposed is a "QueuingConnection" wrapper around a connection that has a narrower interface (i.e. only methods of running that fully materialize the result).