Improve error handling and timeouts for WebSockets

[bridger]

Improves error handling on WebSocket connections. Improvements to WebSocket-Kit intercept errors or timeouts at the ChannelHandler level and expose them to the WebSocket class.

Now, when an error occurs (such as a malformed WebSocket frame) the error is available via the closeCode on WebSocket. Example:

func connected(request: Request, connection: WebSocket) {
  _ = connection.onClose.always { (result) in
      let closeReason = connectionInfo.connection.closeCode ?? .unknown(0)
      // Application-specific cleanup code here
  }

}

[tanner0101]

This PR relies on vapor/websocket-kit#61 now as vapor/websocket-kit#59 was closed.

[tanner0101]

I guess I should also add a bump to Package.swift when vapor/websocket-kit#59 is merged and there is a new beta release

Yes, that would be great. The new version number is: 2.0.0-beta.2.5

Could you also update the PR title and body to formatted as release notes? Examples can be seen here: https://github.com/vapor/vapor/releases. Once merged this will be released automatically.

[bridger]

Thanks for the reviews @tanner0101! I've updated this PR.

[tanner0101]

Thanks!

[tanner0101]

These changes are now available in 4.0.0-beta.4.2