feat: add json format output to cron:list command

This makes it easier to parse output in a machine-readable format - such as when interacting with cron tasks via jq for writing tests.

plugins/cron/src/subcommands/subcommands.go

@@ -20,9 +20,10 @@ func main() {
 	switch subcommand {
 	case "list":
 		args := flag.NewFlagSet("cron:list", flag.ExitOnError)
+		format := args.String("format", "stdout", "format: [ stdout | json ]")
 		args.Parse(os.Args[2:])
 		appName := args.Arg(0)
-		err = cron.CommandList(appName)
+		err = cron.CommandList(appName, *format)
 	case "report":
 		args := flag.NewFlagSet("cron:report", flag.ExitOnError)
 		format := args.String("format", "stdout", "format: [ stdout | json ]")