Add test to read aloud book for language changes

Additional languages in an ebook should be marked up in the XHTML. Then the correct voice is spoken by a screen reader and the correct translation table is used for braille.

We should add a test to check whether the read-aloud voice switches correctly for read-aloud.

Start by reviewing the repository's XHTML test content and existing accessibility test conventions. Add a test covering additional language markup in ebook content for read-aloud, and verify that the expected voice switches correctly for the language change.

Written by the indexing model from the issue text.