Add Snell protocol. Refactor MASQUE HTTP/2, Fair Queue. Update XHTTP, OpenVPN, Sudoku, Fallback. Fixes

include/snell.go

@@ -0,0 +1,17 @@
+//go:build with_snell
+
+package include
+
+import (
+	"github.com/sagernet/sing-box/adapter/inbound"
+	"github.com/sagernet/sing-box/adapter/outbound"
+	"github.com/sagernet/sing-box/protocol/snell"
+)
+
+func registerSnellInbound(registry *inbound.Registry) {
+	snell.RegisterInbound(registry)
+}
+
+func registerSnellOutbound(registry *outbound.Registry) {
+	snell.RegisterOutbound(registry)
+}