Initial mediator package #1

Build @chrismichaelps/pudu-lang-mediator 0.1.0 against Pudu 0.1.3: in-process messaging between the parts of a Pudu program.

Scope:

• Requests with and without a response, notifications with any number of handlers, and stream requests.
• Per-kind and open pipeline behaviors, stream behaviors, pre- and post-processors, exception handlers and exception actions, in one documented order.
• Notification publishing strategies: sequential (stop at the first failure), parallel, bounded, and continuing; custom strategies.
• Untyped dispatch of requests, notifications, and streams through envelopes.
• Sender and publisher interfaces, cancellation, typed context items, and a pull reader for streams.
• Integration behaviors for validation, logging, and resilience.
• The project files, CI, the design vault, examples, mutation testing, and the GitHub wiki API docs.