[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/enginelib/__init__.py

@@ -0,0 +1,143 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# lint: pylint
+"""Engine related implementations
+
+.. note::
+
+   The long term goal is to modularize all relevant implementations to the
+   engines here in this Python package.  In addition to improved modularization,
+   this will also be necessary in part because the probability of circular
+   imports will increase due to the increased typification of implementations in
+   the future.
+
+   ToDo:
+
+   - move :py:obj:`searx.engines.load_engine` to a new module `searx.enginelib`.
+"""
+
+
+from __future__ import annotations
+from typing import Union, Dict, List, Callable, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from searx.enginelib import traits
+
+
+class Engine:  # pylint: disable=too-few-public-methods
+    """Class of engine instances build from YAML settings.
+
+    Further documentation see :ref:`general engine configuration`.
+
+    .. hint::
+
+       This class is currently never initialized and only used for type hinting.
+    """
+
+    # Common options in the engine module
+
+    engine_type: str
+    """Type of the engine (:origin:`searx/search/processors`)"""
+
+    paging: bool
+    """Engine supports multiple pages."""
+
+    time_range_support: bool
+    """Engine supports search time range."""
+
+    safesearch: bool
+    """Engine supports SafeSearch"""
+
+    language_support: bool
+    """Engine supports languages (locales) search."""
+
+    language: str
+    """For an engine, when there is ``language: ...`` in the YAML settings the engine
+    does support only this one language:
+
+    .. code:: yaml
+
+      - name: google french
+        engine: google
+        language: fr
+    """
+
+    region: str
+    """For an engine, when there is ``region: ...`` in the YAML settings the engine
+    does support only this one region::
+
+    .. code:: yaml
+
+      - name: google belgium
+        engine: google
+        region: fr-BE
+    """
+
+    fetch_traits: Callable
+    """Function to to fetch engine's traits from origin."""
+
+    traits: traits.EngineTraits
+    """Traits of the engine."""
+
+    # settings.yml
+
+    categories: List[str]
+    """Tabs, in which the engine is working."""
+
+    name: str
+    """Name that will be used across SearXNG to define this engine.  In settings, on
+    the result page .."""
+
+    engine: str
+    """Name of the python file used to handle requests and responses to and from
+    this search engine (file name from :origin:`searx/engines` without
+    ``.py``)."""
+
+    enable_http: bool
+    """Enable HTTP (by default only HTTPS is enabled)."""
+
+    shortcut: str
+    """Code used to execute bang requests (``!foo``)"""
+
+    timeout: float
+    """Specific timeout for search-engine."""
+
+    display_error_messages: bool
+    """Display error messages on the web UI."""
+
+    proxies: dict
+    """Set proxies for a specific engine (YAML):
+
+    .. code:: yaml
+
+       proxies :
+         http:  socks5://proxy:port
+         https: socks5://proxy:port
+    """
+
+    disabled: bool
+    """To disable by default the engine, but not deleting it.  It will allow the
+    user to manually activate it in the settings."""
+
+    inactive: bool
+    """Remove the engine from the settings (*disabled & removed*)."""
+
+    about: dict
+    """Additional fileds describing the engine.
+
+    .. code:: yaml
+
+       about:
+          website: https://example.com
+          wikidata_id: Q306656
+          official_api_documentation: https://example.com/api-doc
+          use_official_api: true
+          require_api_key: true
+          results: HTML
+    """
+
+    # deprecated properties
+
+    _fetch_supported_languages: Callable  # deprecated use fetch_traits
+    supported_languages: Union[List[str], Dict[str, str]]  # deprecated use traits
+    language_aliases: Dict[str, str]  # deprecated not needed when using triats
+    supported_languages_url: str  # deprecated not needed when using triats