TUN-9469: Centralize UDP origin proxy dialing as ingress service

Introduces a new `UDPOriginProxy` interface and `UDPOriginService`
to standardize how UDP connections are dialed to origins. Allows for
future overrides of the ingress service for specific dial destinations.

Simplifies dependency injection for UDP dialing throughout both datagram
v2 and v3 by using the same ingress service. Previous invocations called
into a DialUDP function in the ingress package that was a light
wrapper over `net.DialUDP`. Now a reference is passed into both datagram
controllers that allows more control over the DialUDP method.

Closes TUN-9469

quic/v3/manager.go

@@ -2,12 +2,11 @@ package v3
 
 import (
 	"errors"
-	"net"
-	"net/netip"
 	"sync"
 
 	"github.com/rs/zerolog"
 
+	"github.com/cloudflare/cloudflared/ingress"
 	"github.com/cloudflare/cloudflared/management"
 
 	cfdflow "github.com/cloudflare/cloudflared/flow"
@@ -38,18 +37,16 @@ type SessionManager interface {
 	UnregisterSession(requestID RequestID)
 }
 
-type DialUDP func(dest netip.AddrPort) (*net.UDPConn, error)
-
 type sessionManager struct {
 	sessions     map[RequestID]Session
 	mutex        sync.RWMutex
-	originDialer DialUDP
+	originDialer ingress.UDPOriginProxy
 	limiter      cfdflow.Limiter
 	metrics      Metrics
 	log          *zerolog.Logger
 }
 
-func NewSessionManager(metrics Metrics, log *zerolog.Logger, originDialer DialUDP, limiter cfdflow.Limiter) SessionManager {
+func NewSessionManager(metrics Metrics, log *zerolog.Logger, originDialer ingress.UDPOriginProxy, limiter cfdflow.Limiter) SessionManager {
 	return &sessionManager{
 		sessions:     make(map[RequestID]Session),
 		originDialer: originDialer,
@@ -76,7 +73,7 @@ func (s *sessionManager) RegisterSession(request *UDPSessionRegistrationDatagram
 	}
 
 	// Attempt to bind the UDP socket for the new session
-	origin, err := s.originDialer(request.Dest)
+	origin, err := s.originDialer.DialUDP(request.Dest)
 	if err != nil {
 		return nil, err
 	}