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/embedded.go

@@ -23,20 +23,23 @@ import (
 	"github.com/urfave/cli/v3"
 )
 
-// CmdEmbedded represents the available extract sub-command.
-var (
-	CmdEmbedded = &cli.Command{
+var matchedAssetFiles []assetFile
+
+func newEmbeddedCommand() *cli.Command {
+	return &cli.Command{
 		Name:        "embedded",
 		Usage:       "Extract embedded resources",
 		Description: "A command for extracting embedded resources, like templates and images",
 		Commands: []*cli.Command{
-			subcmdList,
-			subcmdView,
-			subcmdExtract,
+			newEmbeddedListCommand(),
+			newEmbeddedViewCommand(),
+			newEmbeddedExtractCommand(),
 		},
 	}
+}
 
-	subcmdList = &cli.Command{
+func newEmbeddedListCommand() *cli.Command {
+	return &cli.Command{
 		Name:   "list",
 		Usage:  "List files matching the given pattern",
 		Action: runList,
@@ -48,8 +51,10 @@ var (
 			},
 		},
 	}
+}
 
-	subcmdView = &cli.Command{
+func newEmbeddedViewCommand() *cli.Command {
+	return &cli.Command{
 		Name:   "view",
 		Usage:  "View a file matching the given pattern",
 		Action: runView,
@@ -61,8 +66,10 @@ var (
 			},
 		},
 	}
+}
 
-	subcmdExtract = &cli.Command{
+func newEmbeddedExtractCommand() *cli.Command {
+	return &cli.Command{
 		Name:   "extract",
 		Usage:  "Extract resources",
 		Action: runExtract,
@@ -91,9 +98,7 @@ var (
 			},
 		},
 	}
-
-	matchedAssetFiles []assetFile
-)
+}
 
 type assetFile struct {
 	fs   *assetfs.LayeredFS