appc: factor app connector arguments into a Config type (#17389)

Replace the positional arguments to NewAppConnector with a Config struct.
Update the existing uses. Other than the API change, there are no functional
changes in this commit.

Updates #15160
Updates #17192

Change-Id: Ibf37f021372155a4db8aaf738f4b4f2c746bf623
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>

ipn/ipnlocal/local_test.go

@@ -2309,9 +2309,11 @@ func TestOfferingAppConnector(t *testing.T) {
 			t.Fatal("unexpected offering app connector")
 		}
 		if shouldStore {
-			b.appConnector = appc.NewAppConnector(t.Logf, nil, &appc.RouteInfo{}, fakeStoreRoutes)
+			b.appConnector = appc.NewAppConnector(appc.Config{
+				Logf: t.Logf, RouteInfo: &appc.RouteInfo{}, StoreRoutesFunc: fakeStoreRoutes,
+			})
 		} else {
-			b.appConnector = appc.NewAppConnector(t.Logf, nil, nil, nil)
+			b.appConnector = appc.NewAppConnector(appc.Config{Logf: t.Logf})
 		}
 		if !b.OfferingAppConnector() {
 			t.Fatal("unexpected not offering app connector")
@@ -2370,9 +2372,14 @@ func TestObserveDNSResponse(t *testing.T) {
 
 		rc := &appctest.RouteCollector{}
 		if shouldStore {
-			b.appConnector = appc.NewAppConnector(t.Logf, rc, &appc.RouteInfo{}, fakeStoreRoutes)
+			b.appConnector = appc.NewAppConnector(appc.Config{
+				Logf:            t.Logf,
+				RouteAdvertiser: rc,
+				RouteInfo:       &appc.RouteInfo{},
+				StoreRoutesFunc: fakeStoreRoutes,
+			})
 		} else {
-			b.appConnector = appc.NewAppConnector(t.Logf, rc, nil, nil)
+			b.appConnector = appc.NewAppConnector(appc.Config{Logf: t.Logf, RouteAdvertiser: rc})
 		}
 		b.appConnector.UpdateDomains([]string{"example.com"})
 		b.appConnector.Wait(context.Background())