Bugfix: The DeepL dropdown offers editors the languages they may edit 

Description 

In TYPO3 v13 the list module shows a dropdown to create a page translation with DeepL. For a backend user without admin rights, the check of the language permission was inverted: the dropdown skipped every language the user is allowed to edit and offered only those the user is not allowed to edit.

An editor whose groups allow all languages, which is the case when no language is selected in "Limit to languages", got no dropdown at all. An editor restricted to some languages was offered exactly the other ones, and creating such a translation failed on the missing permission.

Administrators were not affected. The check came with 5.1.4 and 6.0.0.

Impact 

The dropdown offers a backend user without admin rights the languages the user is allowed to edit, provided the user has the permission to translate with DeepL.

See pull request #690.