### Problem Description
I use ubuntu linux. my system language is Chinese, but the dialog button labels is English by default. I found the buttonLabel option from the API to set the label of the save or open button, but the label of the cancel button is not supported.

### Proposed Solution
Support customizing cancel button label in Open and Save dialogs

shell/browser/ui/file_dialog_gtk.cc
gtk_widget_destroy(dialog_);
    if (parent_)
      parent_->SetEnabled(true);
  }
  void SetupOpenProperties(int properties) {
    const auto hasProp = [properties](OpenFileDialogProperty prop) {
      return gboolean((properties & prop) != 0);
    };
    auto* file_chooser = GTK_FILE_CHOOSER(dialog());
    gtk_file_chooser_set_select_multiple(file_chooser,
                                         hasProp(OPEN_DIALOG_MULTI_SELECTIONS));
    gtk_file_chooser_set_show_hidden(file_chooser,
                                     hasProp(OPEN_DIALOG_SHOW_HIDDEN_FILES));
  }
  void SetupSaveProperties(int properties) {
    const auto hasProp = [properties](SaveFileDialogProperty prop) {
      return gboolean((properties & prop) != 0);
    };
    auto* file_chooser = GTK_FILE_CHOOSER(dialog());
    gtk_file_chooser_set_show_hidden(file_chooser,
                                     hasProp(SAVE_DIALOG_SHOW_HIDDEN_FILES));
    gtk_file_chooser_set_do_overwrite_confirmation(
        file_chooser, hasProp(SAVE_DIALOG_SHOW_OVERWRITE_CONFIRMATION));
  }
  void RunAsynchronous() {