* Added initial connection middleware pipeline
- Implemented IConnectionBuilder on ListenOptions. Kept IConnectionAdapter for now.
- Delay the configure callback for ListenOptions until the server has started.
- Added ConnectionLimitMiddleware and HttpConnectionMiddleware
- Expose ConnectionAborted and ConnectionClosed on ConnectionContext and
IConnectionTransportFeature
- Updated the tests
- Removed IConnectionApplicationFeature
- Moved Application to IConnectionTransportFeature
