The pass-through NullDriverCapabilityInvoker returns the call-site task directly, so it
never exercises the real invoker's internal `pipeline.ExecuteAsync(...).ConfigureAwait(false)`.
Adds a test-only Core reference to Runtime.Tests (the PRODUCTION Runtime assembly stays
Polly-free via the seam) and a discovery test that drives DriverInstanceActor through a real
CapabilityInvoker over a genuinely-yielding ITagDiscovery driver — proving the invoker's
internal ConfigureAwait(false) does NOT leak to the actor's own await, so the post-await
Context.Parent.Tell still runs (DiscoveredNodesReady arrives). Runtime.Tests 358, Core.Tests 238.
Joseph Doherty