refs #17850_merge [finc: BARF] BS-accessibility plugin localization

* creates a German version in finc-accessibility
* translate caroussel terms to German
* use empty standard version to overwrite outdated default
* use language specific versions for German and English in layout template
* add template for similar items to load accessibility plugin as ajax tab
** necessary to register new elements loaded by ajax

co-authored by: Robert Lange <robert.lange@uni-leipzig.de>