Inject this in place of the driver's private SDK client.
Conformance-config hook: next call fails at the given site.
Conformance-config hook: next non-streaming call succeeds.
Conformance-config hook: next streaming call emits chunks, aborts the controller, then dies like an aborted SDK stream.
Conformance-config hook: next streaming call emits these chunks then completes.
The scriptable seam handed to a provider conformance test file.