Switch cmd/ to use constructor functions. (#36962)

This is a step towards potentially splitting command groups into their
own folders to clean up `cmd/` as one folder for all cli commands.
Returning fresh command instances will also aid in adding tests as you
don't need to concern yourself with the whole command tree being one
mutable variable.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

cmd/serv.go

@@ -35,22 +35,23 @@ import (
 	"github.com/urfave/cli/v3"
 )
 
-// CmdServ represents the available serv sub-command.
-var CmdServ = &cli.Command{
-	Name:        "serv",
-	Usage:       "(internal) Should only be called by SSH shell",
-	Description: "Serv provides access auth for repositories",
-	Hidden:      true, // Internal commands shouldn't be visible in help
-	Before:      PrepareConsoleLoggerLevel(log.FATAL),
-	Action:      runServ,
-	Flags: []cli.Flag{
-		&cli.BoolFlag{
-			Name: "enable-pprof",
+func newServCommand() *cli.Command {
+	return &cli.Command{
+		Name:        "serv",
+		Usage:       "(internal) Should only be called by SSH shell",
+		Description: "Serv provides access auth for repositories",
+		Hidden:      true, // Internal commands shouldn't be visible in help
+		Before:      PrepareConsoleLoggerLevel(log.FATAL),
+		Action:      runServ,
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name: "enable-pprof",
+			},
+			&cli.BoolFlag{
+				Name: "debug",
+			},
 		},
-		&cli.BoolFlag{
-			Name: "debug",
-		},
-	},
+	}
 }
 
 func setup(ctx context.Context, debug bool) {