Tracking Issue: QUIC testing

QUIC Testing Check-list.. set up as a tracking issue so that folks can follow along / help if they want. This should also give folks a good idea of the size of the work required still to finish. When discussing any particular item, please refer to the number for easier reference. * 1.0.0 Core Protocol Implementation * 1.1.0 Endpoint Testing * [x] 1.1.1 Endpoint creation with various configurations * [x] 1.1.2 IPv4 binding * [x] 1.1.3 IPv6 binding * [x] 1.1.4 IPv6-only mode * [ ] TODO: The ergonomics of configuring for ipv6 are... not great. Need to revisit this part of the JS API. * [x] 1.1.5 Dual-stack mode * [x] 1.1.6 Random port allocation * [x] 1.1.7 Specific port binding * [x] 1.1.8 Port reuse scenarios * [x] 1.1.9 Endpoint can be use for both client and server * 1.2.0 Endpoint lifecycle * [x] 1.2.1 Graceful shutdown with active sessions * 1.2.2 Forced shutdown/destroy * [x] 1.2.2.1 With no sessions * [x] 1.2.2.2 With sessions, no streams * [x] 1.2.2.3 With sessions and streams * [x] 1.2.3 Cleanup of sessions on endpoint graceful close * [x] 1.2.4 Async.dispose implementation * 1.3.0 Endpoint options validation * [x] 1.3.1 UDP receive/send buffer sizes * [x] 1.3.2 UDP TTL configuration * [x] 1.3.3 Token expiration settings * [x] 1.3.4 Retry token expiration * [x] 1.3.5 Connection limits (per-host, total) * [x] 1.3.6 Stateless reset limits * [x] 1.3.7 Address LRU cache sizing * [x] 1.3.8 Reset token secret handling * [x] 1.3.9 Token secret handling * 1.4.0 Server mode * [x] 1.4.1 Listen configuration * [x] 1.4.2 Busy state handling * [x] 1.4.3 Rejection of new connections when busy * [x] 1.4.4 Multiple session handling * [x] 1.4.5 Session acceptance callback * 1.5.0 Client mode * [x] 1.5.1 Connect to remote endpoint * [x] 1.5.2 Multiple concurrent connections * [x] 1.5.3 Connection to same host/port * [x…