Improve Category and Option (serialization, attributes)

app/config/services.yml

mongo_operations

src/Biopen/GeoDirectoryBundle/Admin/CategoryAdmin.php

src/Biopen/GeoDirectoryBundle/Admin/OptionAdmin.php

...ectoryBundle/Controller/Admin/CategoryAdminController.php

...n/GeoDirectoryBundle/Controller/ElementFormController.php

src/Biopen/GeoDirectoryBundle/Document/Category.php

src/Biopen/GeoDirectoryBundle/Document/Option.php

...Bundle/Resources/views/admin/tree_category_item.html.twig

...views/element-form/form-partials/category-field.html.twig

...pen/GeoDirectoryBundle/Services/RandomCreationService.php