Preserve wikipedia language setting for wikiless redirects

Wikipedia -> Wikiless redirects always result in an english language
result, even if the Wikipedia result would've been in a non-english
language. This is due to Wikipedia using language specific subdomains
(i.e. de.wikipedia.org, en.wikipedia.org, etc) whereas Wikiless uses a
"lang" url param.

This has been fixed by inspecting the subdomain of the wikipedia link
and passing that value to Wikiless as the lang param if it's determined
to be a language specific value (currently just looking for a 2-char
subdomain).

See #805

app/utils/results.py

@@ -134,7 +134,16 @@ def get_site_alt(link: str) -> str:
         if not hostname or site_key not in hostname or not SITE_ALTS[site_key]:
             continue
 
-        link = link.replace(hostname, SITE_ALTS[site_key])
+        # Wikipedia -> Wikiless replacements require the subdomain (if it's
+        # a 2-char language code) to be passed as a URL param to Wikiless
+        # in order to preserve the language setting.
+        url_params = ''
+        if 'wikipedia' in hostname:
+            subdomain = hostname.split('.')[0]
+            if len(subdomain) == 2:
+                url_params = f'?lang={subdomain}'
+
+        link = link.replace(hostname, SITE_ALTS[site_key]) + url_params
         for prefix in SKIP_PREFIX:
             link = link.replace(prefix, '//')
         break