Improve tests

[mtrudel]

• Run tests async
• Get rid of sleep calls in tests that were there only to (racily!) capture logs / telemetry, and replace with receive based log / telemetry test helpers
• Test suite speedup of about 10x!
• Add plug to telemetry metadata
• Add plug to logging metadata
• Improve many sad path logging cases to include a full suite of metadata

[mtrudel]

In the interest of review ability I'm going to merge this even though there's still some test improvements to be done. Things 'coming soon' after this goes out:

• Use the same message based approach to log testing for WebSockets. Requires a rethink of how we do logging in the WebSocket stack
• Split http1/request_test.exs into http1/{plug, protocol}_test.exs to mirror the pattern for http2 and websocket