Fields translation path exceeds the maximum menu parts

This issue only occurs on multilingual sites, using i18n module for field translation.

The problem is that the path length for fields translation is too long (@see MENU_MAX_PARTS), so the last component of the path (here the language) is removed.

For example, the path to translate a title field for image entity is something like:
admin/config/media/file-types/manage/image/fields/field_image_title/translate/fr

This path is splitted into 9 parts, but only 8 are supported by Drupal menu system.

The simpliest and logical solution that come to me would be to move the "file types" menu tree to the "structure" part of the administration UI. So the possible menu structure could be:

- Admin
-- Structure
--- File types

This would ensure compatibility with i18n field translation UI.