Add new group display mode for quick form widget

[veve40]

• Add support for grouping properties by the language, for multilingual form properties.
• Centralize sort by priority comparator functions to minimize duplicate code.

[mcaskill]

Summary of a chat between @veve40, @mcaskill, @JoelAlphonso:

• Add support class Sorter with method sortByPriority().
  • Migrate equivalent methods from other classes:
    • sortLanguagesByPriority()
    • sortItemsByPriority()
    • sortGroupsByPriority()
    • sortActionsByPriority()
    • Note: This could just be done for sortLanguagesByPriority() for now and create another pull request to unify others.
• Add HasLanguageSwitcherTrait and HasLanguageSwitcherInterface or maybe as a service class?
  • Migrate methods showLanguageSwitch() from:
    • QuickFormWidget
    • FormSidebarWidget
• Replace method hasL10nFormProperties() on ObjectFormWidget with implementation from QuickFormWidget.

---

Proposed structure for HasLanguageSwitcherTrait:

`HasLanguageSwitcherTrait`

public function showLanguageSwitch()
{
    if ($this->showLanguageSwitch === null) {
        $this->showLanguageSwitch = $this->resolveShowLanguageSwitch();
    }
    return $this->showLanguageSwitch;
}

abstract protected function resolveShowLanguageSwitch();

`QuickFormWidget` / `ObjectFormWidget`

protected function resolveShowLanguageSwitch()
{
    return $this->hasL10nFormProperties();
}

`FormSidebarWidget`

protected function resolveShowLanguageSwitch()
{
    if ($form) {
        return $form->hasL10nFormProperties();
    }

    return false;
}

[mcaskill]

Nice work. All that's missing is adding isDisplayModeLang and showLanguageSwitch to a QuickFormWidget::widgetDataForJs() method to wrap the trigger and event lisener that you moved to quickform.js.