Add label field to task definition

Label is an alternative name for task that replace it when printed in following context eg.:

- log: when given task is up to date and is skipped from execution
- log: when given task is NOT up to date (`--status` command)
- in `--summary` and `--list` commands output

status.go

@@ -22,7 +22,7 @@ func (e *Executor) Status(ctx context.Context, calls ...taskfile.Call) error {
 			return err
 		}
 		if !isUpToDate {
-			return fmt.Errorf(`task: Task "%s" is not up-to-date`, t.Task)
+			return fmt.Errorf(`task: Task "%s" is not up-to-date`, t.Name())
 		}
 	}
 	return nil