[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  [fix] old supported_languages_url is no longer valid since the sources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>

docs/src/searx.engines.peertube.rst

@@ -0,0 +1,19 @@
+.. _peertube engines:
+
+================
+Peertube Engines
+================
+
+.. contents:: Contents
+   :depth: 2
+   :local:
+   :backlinks: entry
+
+
+.. _peertube video engine:
+
+Peertube Video
+==============
+
+.. automodule:: searx.engines.peertube
+  :members: