Update porter to rc.2

[VinozzZ]

• Update go module reference for Porter to 1.0.0-rc.2.
• Update code to match new version
• Use Go 1.18
• Update mixin to support tracing. This doesn't instrument the mixin. It just updates the entrypoint so that it starts a root span and saves the resulting TraceLogger on the context so that later, we can use tracing.StartSpan or tracing.LoggerFromContext and get back an initialized logger.
• Bump default client version
• Update example bundles