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

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

supervisor/metrics.go

@@ -0,0 +1,27 @@
+package supervisor
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/cloudflare/cloudflared/connection"
+)
+
+// Metrics uses connection.MetricsNamespace(aka cloudflared) as namespace and connection.TunnelSubsystem
+// (tunnel) as subsystem to keep them consistent with the previous qualifier.
+
+var (
+	haConnections = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: connection.MetricsNamespace,
+			Subsystem: connection.TunnelSubsystem,
+			Name:      "ha_connections",
+			Help:      "Number of active ha connections",
+		},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(
+		haConnections,
+	)
+}