refactor: Improve handshake resiliency of peer (#95)

* fix: Synchronize peer logging with a channel

We were depending on the close mutex to properly
report connection state. This ensures the RTC
connection is properly closed before returning.

* Disable pion logging

* Remove buffer

* Try ICE servers

* Remove flushed

* Add diagram explaining handshake

* Fix candidate accept ordering

* Add debug logging to peerbroker

* Fix send ordering

* Lock adding ICE candidate

* Add test for negotiating out of order

* Reduce connection to a single negotiation channel

* Improve test times by pre-installing Terraform

* Lock remote session description being applied

* Organize conn

* Revert to multi-channel setup

* Properly close ICE gatherer

* Improve comments

* Try removing buffered candidates

* Buffer local and remote messages

* Log dTLS transport state

* Add pion logging

peer/channel.go

@@ -141,9 +141,9 @@ func (c *Channel) init() {
 		// A DataChannel can disconnect multiple times, so this needs to loop.
 		for {
 			select {
-			case <-c.closed:
+			case <-c.conn.closedRTC:
 				// If this channel was closed, there's no need to close again.
-				return
+				err = c.conn.closeError
 			case <-c.conn.Closed():
 				// If the RTC connection closed with an error, this channel
 				// should end with the same one.