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/restore_repo.go

@@ -13,40 +13,41 @@ import (
 	"github.com/urfave/cli/v3"
 )
 
-// CmdRestoreRepository represents the available restore a repository sub-command.
-var CmdRestoreRepository = &cli.Command{
-	Name:        "restore-repo",
-	Usage:       "Restore the repository from disk",
-	Description: "This is a command for restoring the repository data.",
-	Action:      runRestoreRepository,
-	Flags: []cli.Flag{
-		&cli.StringFlag{
-			Name:    "repo_dir",
-			Aliases: []string{"r"},
-			Value:   "./data",
-			Usage:   "Repository dir path to restore from",
-		},
-		&cli.StringFlag{
-			Name:  "owner_name",
-			Value: "",
-			Usage: "Restore destination owner name",
-		},
-		&cli.StringFlag{
-			Name:  "repo_name",
-			Value: "",
-			Usage: "Restore destination repository name",
-		},
-		&cli.StringFlag{
-			Name:  "units",
-			Value: "",
-			Usage: `Which items will be restored, one or more units should be separated as comma.
+func newRestoreRepositoryCommand() *cli.Command {
+	return &cli.Command{
+		Name:        "restore-repo",
+		Usage:       "Restore the repository from disk",
+		Description: "This is a command for restoring the repository data.",
+		Action:      runRestoreRepository,
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:    "repo_dir",
+				Aliases: []string{"r"},
+				Value:   "./data",
+				Usage:   "Repository dir path to restore from",
+			},
+			&cli.StringFlag{
+				Name:  "owner_name",
+				Value: "",
+				Usage: "Restore destination owner name",
+			},
+			&cli.StringFlag{
+				Name:  "repo_name",
+				Value: "",
+				Usage: "Restore destination repository name",
+			},
+			&cli.StringFlag{
+				Name:  "units",
+				Value: "",
+				Usage: `Which items will be restored, one or more units should be separated as comma.
 wiki, issues, labels, releases, release_assets, milestones, pull_requests, comments are allowed. Empty means all units.`,
+			},
+			&cli.BoolFlag{
+				Name:  "validation",
+				Usage: "Sanity check the content of the files before trying to load them",
+			},
 		},
-		&cli.BoolFlag{
-			Name:  "validation",
-			Usage: "Sanity check the content of the files before trying to load them",
-		},
-	},
+	}
 }
 
 func runRestoreRepository(ctx context.Context, c *cli.Command) error {