[fix] engine - yahoo: rewrite and fix issues

Languages are supported by mapping the language to a domain.  If domain is not
found in :py:obj:`lang2domain` URL ``<lang>.search.yahoo.com`` is used.

BTW: fix issue reported at https://github.com/searx/searx/issues/3020



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>