Provide RuntimeEnv to ExecutionContext #1636

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

#1526 added a MemoryManager along with the concept of a RuntimeEnv, this is awesome. Unfortunately ExecutionContext::new() and ExecutionContext::with_config call RuntimeEnv::new(), which in turn creates a new MemoryManager and DiskManager, which create a temporary directory and print logs, which is decidedly less awesome.

At least within IOx we construct an ExecutionContext for each query, as various settings may change, most notably the catalog. Therefore these logs and especially the directory creation and associated IO (#1637) are problematic.

Describe the solution you'd like

I think it should be possible to pass an extant Arc<RuntimeEnv> to an ExecutionContext, so that multiple different ExecutionContext can share the same resource pool.

Describe alternatives you've considered

We could maintain separate ExecutionContext for each type of query IOx executes, but this is just punting the problem imo. We want to be able to have queries running in different contexts, but on the same pool of resources managed by a RuntimeEnv.

FYI @yjshen