TUN-4597: Add a QUIC server skeleton

- Added a QUIC server to accept streams
- Unit test for this server also tests ALPN
- Temporary echo capability for HTTP ConnectionType

vendor/github.com/cheekybits/genny/generic/generic.go

@@ -0,0 +1,13 @@
+package generic
+
+// Type is the placeholder type that indicates a generic value.
+// When genny is executed, variables of this type will be replaced with
+// references to the specific types.
+//      var GenericType generic.Type
+type Type interface{}
+
+// Number is the placehoder type that indiccates a generic numerical value.
+// When genny is executed, variables of this type will be replaced with
+// references to the specific types.
+//      var GenericType generic.Number
+type Number float64