Yggdrasil+QUIC demo, federation sender tweaks (#1177)

* Initial QUIC work

* Update Yggdrasil demo

* Make sure that the federation sender knows how many pending events are in the database when the worker starts

* QUIC tunables

* pprof

* Don't spin

* Set build info for Yggdrasil

cmd/dendrite-demo-yggdrasil/yggconn/stream.go

@@ -0,0 +1,20 @@
+package yggconn
+
+import (
+	"net"
+
+	"github.com/lucas-clemente/quic-go"
+)
+
+type QUICStream struct {
+	quic.Stream
+	session quic.Session
+}
+
+func (s QUICStream) LocalAddr() net.Addr {
+	return s.session.LocalAddr()
+}
+
+func (s QUICStream) RemoteAddr() net.Addr {
+	return s.session.RemoteAddr()
+}