As an editor I want to enter Lexemes in Dagbani in order to record words in the language.
**Problem:**
`dag` was added for labels on Items in T260037. It can not yet be used for Lexemes.
Comparing the list of codes the API returns for [[https://www.wikidata.org/w/api.php?action=query&meta=wbcontentlanguages&wbclcontext=term&format=json|labels]] and [[https://www.wikidata.org/w/api.php?action=query&meta=wbcontentlanguages&wbclcontext=term-lexicographical&format=json|lexemes]], it seems `dag` is the only code which can be used for labels but not for lexemes. All of the other extra codes in [[https://gerrit.wikimedia.org/g/mediawiki/extensions/Wikibase/+/master/lib/includes/WikibaseContentLanguages.php#59|WikibaseContentLanguages.php]] work fine.
**Acceptance criteria:**
* dag is an allowed language for Lexemes
**Notes:**
* Based on discussion with Lucas we want to add dag to the list of $additionalLanguages in WikibaseLexeme.mediawiki-services.php.