TUN-8728: implement diag/tunnel endpoint

## Summary
The new endpoint returns the current information to be used when calling the diagnostic procedure.
This also adds:
- add indexed connection info and method to extract active connections from connTracker
- add edge address to Event struct and conn tracker
- remove unnecessary event send
- add tunnel configuration handler
- adjust cmd and metrics to create diagnostic server

Closes TUN-8728

connection/control.go

@@ -102,7 +102,7 @@ func (c *controlStream) ServeControlStream(
 	c.observer.metrics.regSuccess.WithLabelValues("registerConnection").Inc()
 
 	c.observer.logConnected(registrationDetails.UUID, c.connIndex, registrationDetails.Location, c.edgeAddress, c.protocol)
-	c.observer.sendConnectedEvent(c.connIndex, c.protocol, registrationDetails.Location)
+	c.observer.sendConnectedEvent(c.connIndex, c.protocol, registrationDetails.Location, c.edgeAddress)
 	c.connectedFuse.Connected()
 
 	// if conn index is 0 and tunnel is not remotely managed, then send local ingress rules configuration

connection/event.go

@@ -1,12 +1,15 @@
 package connection
 
+import "net"
+
 // Event is something that happened to a connection, e.g. disconnection or registration.
 type Event struct {
-	Index     uint8
-	EventType Status
-	Location  string
-	Protocol  Protocol
-	URL       string
+	Index       uint8
+	EventType   Status
+	Location    string
+	Protocol    Protocol
+	URL         string
+	EdgeAddress net.IP
 }
 
 // Status is the status of a connection.

connection/observer.go

@@ -47,7 +47,6 @@ func (o *Observer) RegisterSink(sink EventSink) {
 }
 
 func (o *Observer) logConnected(connectionID uuid.UUID, connIndex uint8, location string, address net.IP, protocol Protocol) {
-	o.sendEvent(Event{Index: connIndex, EventType: Connected, Location: location})
 	o.log.Info().
 		Int(management.EventTypeKey, int(management.Cloudflared)).
 		Str(LogFieldConnectionID, connectionID.String()).
@@ -63,8 +62,8 @@ func (o *Observer) sendRegisteringEvent(connIndex uint8) {
 	o.sendEvent(Event{Index: connIndex, EventType: RegisteringTunnel})
 }
 
-func (o *Observer) sendConnectedEvent(connIndex uint8, protocol Protocol, location string) {
-	o.sendEvent(Event{Index: connIndex, EventType: Connected, Protocol: protocol, Location: location})
+func (o *Observer) sendConnectedEvent(connIndex uint8, protocol Protocol, location string, edgeAddress net.IP) {
+	o.sendEvent(Event{Index: connIndex, EventType: Connected, Protocol: protocol, Location: location, EdgeAddress: edgeAddress})
 }
 
 func (o *Observer) SendURL(url string) {