OrchestrationClient input binding detection to use bindingDefinitions.

Now that we're using the `@azure/functions` TypeScript definitions, we should change the orchestrationClient input binding detector to use the information from `Context.bindingDefinitions`.

Locate the orchestrationClient input binding detector and inspect how Context.bindingDefinitions is exposed by the @azure/functions TypeScript definitions. Update the detector to use that binding-definition information, then verify that orchestration client input binding detection behaves as intended.

Written by the indexing model from the issue text.