add server fronting for search endpoint

This also implements some of the quirks of free-text search of the
V1 API, in particular, search for categories and coordinates.

nominatim/api/results.py

@@ -228,6 +228,12 @@ class SearchResults(List[SearchResult]):
         May be empty when no result was found.
     """
 
+    def localize(self, locales: Locales) -> None:
+        """ Apply the given locales to all results.
+        """
+        for result in self:
+            result.localize(locales)
+
 
 def _filter_geometries(row: SaRow) -> Dict[str, str]:
     return {k[9:]: v for k, v in row._mapping.items() # pylint: disable=W0212