Menu item extras templates and suggestions are only enabled for menus with fields

Problem/Motivation

Menu item extras template suggestions are only enabled for menus with custom fields.

Steps to reproduce

• Create a menu with no fields
• Add a display mode to the menu
• Enable twig debugging
• Confirm that no menu item extra template suggestions are available

Notes

The current behavior is that a menu link content entity must have a custom field for menu item extras templates and suggestions to be applicable.

@see \Drupal\menu_item_extras\Utility\Utility::checkBundleHasExtraFieldsThanEntity
@see \menu_item_extras_preprocess_block()
@see \menu_item_extras_preprocess_menu()
@see \menu_item_extras_theme_suggestions_menu()

Proposed resolution

OPTION 1:
Check if a menu has display modes and allow menu item extras templates and suggestions to be applicable.

OPTION 2:
Check if a menu is not locked (aka not an admin or devel menu) and allow menu item extras templates and suggestions to be applicable.

OPTION 3:
Leave the AS-IS and require a field to be added to allow menu item extras templates and suggestions to be applicable.

Remaining tasks

• Determine the best option
• Create MR
• Review MR
• Merge MR

User interface changes

N/A

API changes

Possibly adding new utilities including Utility::checkBundleHasExtraViewModes

Data model changes

N/A