feat: add tailnet v2 API support to coordinate endpoint (#11228)

closes #10532

Adds v2 support to the /coordinate endpoint via a query parameter.

v1 already has test cases, and we haven't implemented v2 at the client yet, so the only new test case is an unsupported version.

coderd/coderd.go

@@ -473,6 +473,11 @@ func New(options *Options) *API {
 			Cache: wsconncache.New(api._dialWorkspaceAgentTailnet, 0),
 		}
 	}
+	api.TailnetClientService, err = tailnet.NewClientService(
+		api.Logger.Named("tailnetclient"), &api.TailnetCoordinator)
+	if err != nil {
+		api.Logger.Fatal(api.ctx, "failed to initialize tailnet client service", slog.Error(err))
+	}
 
 	workspaceAppsLogger := options.Logger.Named("workspaceapps")
 	if options.WorkspaceAppsStatsCollectorOptions.Logger == nil {
@@ -1061,6 +1066,7 @@ type API struct {
 	Auditor                           atomic.Pointer[audit.Auditor]
 	WorkspaceClientCoordinateOverride atomic.Pointer[func(rw http.ResponseWriter) bool]
 	TailnetCoordinator                atomic.Pointer[tailnet.Coordinator]
+	TailnetClientService              *tailnet.ClientService
 	QuotaCommitter                    atomic.Pointer[proto.QuotaCommitter]
 	// WorkspaceProxyHostsFn returns the hosts of healthy workspace proxies
 	// for header reasons.