[refactor] typification of SearXNG / EngineResults

In [1] and [2] we discussed the need of a Result.results property and how we can
avoid unclear code.  This patch implements a class for the reslut-lists of
engines::

    searx.result_types.EngineResults

A simple example for the usage in engine development::

    from searx.result_types import EngineResults
    ...
    def response(resp) -> EngineResults:
        res = EngineResults()
        ...
        res.add( res.types.Answer(answer="lorem ipsum ..", url="https://example.org") )
        ...
        return res

[1] https://github.com/searxng/searxng/pull/4183#pullrequestreview-257400034
[2] https://github.com/searxng/searxng/pull/4183#issuecomment-2614301580
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/engines/openstreetmap.py

@@ -13,7 +13,7 @@ from flask_babel import gettext
 from searx.data import OSM_KEYS_TAGS, CURRENCIES
 from searx.external_urls import get_external_url
 from searx.engines.wikidata import send_wikidata_query, sparql_string_escape, get_thumbnail
-from searx.result_types import Answer
+from searx.result_types import EngineResults
 
 # about
 about = {
@@ -141,8 +141,8 @@ def request(query, params):
     return params
 
 
-def response(resp):
-    results = []
+def response(resp) -> EngineResults:
+    results = EngineResults()
 
     nominatim_json = resp.json()
     user_language = resp.search_params['language']
@@ -152,10 +152,12 @@ def response(resp):
         l = re.findall(r"\s*(.*)\s+to\s+(.+)", resp.search_params["query"])
     if l:
         point1, point2 = [urllib.parse.quote_plus(p) for p in l[0]]
-        Answer(
-            results=results,
-            answer=gettext('Show route in map ..'),
-            url=f"{route_url}/?point={point1}&point={point2}",
+
+        results.add(
+            results.types.Answer(
+                answer=gettext('Show route in map ..'),
+                url=f"{route_url}/?point={point1}&point={point2}",
+            )
         )
 
     # simplify the code below: make sure extratags is a dictionary