[mod] Peertube: re-engineered & upgrade to data_type: traits_v1

- fetch_traits(): Fetch languages from peertube's search-index source code.

  [mod] Include migration of the request methode from 'supported_languages'
        to 'traits' (EngineTraits) object.
  [fix] old supported_languages_url is no longer valid since the sources
        has been moved to a different path.

- fixed code to pass pylint
- request(): complete re-implementation based on the API docs [1]
- response(): complete re-implementation, adds serveral fields missed before
- add source code documentation

[1] https://docs.joinpeertube.org/api-rest-reference.html#tag/Search/operation/searchVideos

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

searx/data/engine_traits.json

@@ -1468,31 +1468,32 @@
   "peertube": {
     "all_locale": null,
     "custom": {},
-    "data_type": "supported_languages",
-    "languages": {},
+    "data_type": "traits_v1",
+    "languages": {
+      "ca": "ca",
+      "cs": "cs",
+      "de": "de",
+      "el": "el",
+      "en": "en",
+      "eo": "eo",
+      "es": "es",
+      "eu": "eu",
+      "fi": "fi",
+      "fr": "fr",
+      "gd": "gd",
+      "it": "it",
+      "ja": "ja",
+      "nl": "nl",
+      "pl": "pl",
+      "pt": "pt",
+      "ru": "ru",
+      "sv": "sv",
+      "zh": "zh",
+      "zh_Hans": "zh",
+      "zh_Hant": "zh"
+    },
     "regions": {},
-    "supported_languages": [
-      "ca",
-      "cs",
-      "de",
-      "el",
-      "en",
-      "eo",
-      "es",
-      "eu",
-      "fi",
-      "fr",
-      "gd",
-      "it",
-      "ja",
-      "nl",
-      "oc",
-      "pl",
-      "pt",
-      "ru",
-      "sv",
-      "zh"
-    ]
+    "supported_languages": {}
   },
   "qwant": {
     "all_locale": null,
@@ -4531,4 +4532,4 @@
       "zh_cht"
     ]
   }
-}
+}