[mod] botdetection - improve ip_limit and link_token methods

- counting requests in LONG_WINDOW and BURST_WINDOW is not needed when the
  request is validated by the link_token method [1]

- renew a ping-key on validation [2], this is needed for infinite scrolling,
  where no new token (CSS) is loaded. / this does not fix the BURST_MAX issue in
  the vanilla limiter

- normalize the counter names of the ip_limit method to 'ip_limit.*'

- just integrate the ip_limit method straight forward in the limiter plugin /
  non intermediate code --> ip_limit now returns None or a werkzeug.Response
  object that can be passed by the plugin to the flask application / non
  intermediate code that returns a tuple

[1] https://github.com/searxng/searxng/pull/2357#issuecomment-1566113277
[2] https://github.com/searxng/searxng/pull/2357#discussion_r1208542206
[3] https://github.com/searxng/searxng/pull/2357#issuecomment-1566125979

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

searx/botdetection/http_accept_encoding.py

@@ -16,14 +16,16 @@ bot if the Accept-Encoding_ header ..
 """
 # pylint: disable=unused-argument
 
-from typing import Optional, Tuple
+from typing import Optional
 import flask
+import werkzeug
 
 from searx.tools import config
+from ._helpers import too_many_requests
 
 
-def filter_request(request: flask.Request, cfg: config.Config) -> Optional[Tuple[int, str]]:
+def filter_request(request: flask.Request, cfg: config.Config) -> Optional[werkzeug.Response]:
     accept_list = [l.strip() for l in request.headers.get('Accept-Encoding', '').split(',')]
     if not ('gzip' in accept_list or 'deflate' in accept_list):
-        return 429, "bot detected, HTTP header Accept-Encoding did not contain gzip nor deflate"
+        return too_many_requests(request, "HTTP header Accept-Encoding did not contain gzip nor deflate")
     return None