[mod] replace engines_languages.json by engines_traits.json

Implementations of the *traits* of the engines.

Engine's traits are fetched from the origin engine and stored in a JSON file in
the *data folder*.  Most often traits are languages and region codes and their
mapping from SearXNG's representation to the representation in the origin search
engine.

To load traits from the persistence::

    searx.enginelib.traits.EngineTraitsMap.from_data()

For new traits new properties can be added to the class::

    searx.enginelib.traits.EngineTraits

.. hint::

   Implementation is downward compatible to the deprecated *supported_languages
   method* from the vintage implementation.

   The vintage code is tagged as *deprecated* an can be removed when all engines
   has been ported to the *traits method*.

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

searx/data/__init__.py

@@ -7,7 +7,7 @@
 """
 
 __all__ = [
-    'ENGINES_LANGUAGES',
+    'ENGINE_TRAITS',
     'CURRENCIES',
     'USER_AGENTS',
     'EXTERNAL_URLS',
@@ -42,7 +42,6 @@ def ahmia_blacklist_loader():
         return f.read().split()
 
 
-ENGINES_LANGUAGES = _load('engines_languages.json')
 CURRENCIES = _load('currencies.json')
 USER_AGENTS = _load('useragents.json')
 EXTERNAL_URLS = _load('external_urls.json')
@@ -50,3 +49,4 @@ WIKIDATA_UNITS = _load('wikidata_units.json')
 EXTERNAL_BANGS = _load('external_bangs.json')
 OSM_KEYS_TAGS = _load('osm_keys_tags.json')
 ENGINE_DESCRIPTIONS = _load('engine_descriptions.json')
+ENGINE_TRAITS = _load('engine_traits.json')