[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/limiter.py

@@ -42,6 +42,7 @@ from pathlib import Path
 import flask
 import pytomlpp as toml
 
+from searx import logger
 from searx.tools import config
 from searx.botdetection import (
     http_accept,
@@ -62,7 +63,13 @@ CFG_DEPRECATED = {
     # "dummy.old.foo": "config 'dummy.old.foo' exists only for tests.  Don't use it in your real project config."
 }
 
-CFG = config.Config({}, {})
+CFG = None
+
+
+def get_cfg() -> config.Config:
+    if CFG is None:
+        init_cfg(logger)
+    return CFG
 
 
 def init_cfg(log):
@@ -73,7 +80,7 @@ def init_cfg(log):
         log.warning("missing config file: %s", LIMITER_CFG)
         return
 
-    log.warning("load config file: %s", LIMITER_CFG)
+    log.info("load config file: %s", LIMITER_CFG)
     try:
         upd_cfg = toml.load(LIMITER_CFG)
     except toml.DecodeError as exc: