[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>

searx/data/engines_languages.json

@@ -28418,7 +28418,7 @@
     "sv",
     "th",
     "tr",
-    "zh-CHS",
-    "zh-CHT"
+    "zh_chs",
+    "zh_cht"
   ]
 }