plug-ins: be consistent and use Name in Add Unit

The name was changed from ID to Name in the Unit Editor, so it makes
sense to do the same for the Add Unit Dialog.

plug-ins/common/unit-editor.c

@@ -449,7 +449,7 @@ new_unit_dialog (GtkWindow *main_window,
                           gimp_unit_get_name (template));
     }
   gimp_grid_attach_aligned (GTK_GRID (grid), 0, 0,
-                            _("_ID:"), 0.0, 0.5,
+                            _("_Name:"), 0.0, 0.5,
                             entry, 1);
 
   gimp_help_set_help_data (entry, gettext (columns[NAME].help), NULL);