TUN-5749: Refactor cloudflared to pave way for reconfigurable ingress

- Split origin into supervisor and proxy packages
- Create configManager to handle dynamic config

supervisor/external_control.go

@@ -0,0 +1,21 @@
+package supervisor
+
+import (
+	"time"
+)
+
+type ReconnectSignal struct {
+	// wait this many seconds before re-establish the connection
+	Delay time.Duration
+}
+
+// Error allows us to use ReconnectSignal as a special error to force connection abort
+func (r ReconnectSignal) Error() string {
+	return "reconnect signal"
+}
+
+func (r ReconnectSignal) DelayBeforeReconnect() {
+	if r.Delay > 0 {
+		time.Sleep(r.Delay)
+	}
+}