[Form] Add choice_translation_locale option for Intl choice types #9657
Description
This PR adds possibility to show the list of elements for a custom locale different to the current one and proposes also deprecate the ChoiceLoaderInterface implementation from all of them, moving it to a separate class.
@yceruto will you have some time before Symfony 4.1 is released at the end of May to work on a PR to document this feature? Thanks!