[Windows] Security model for files permissions - STEP 1 (#6893)

This PR is the first part of #6497 to ease the integration, following the new plan propose by @bmw here: #6497 (comment)

This step 1 refactor existing certbot.compat module into certbot.compat.misc, without any logic changed. Package certbot.compat will host the new modules that constitute the security model for Windows.

* Create the certbot.compat package. Move logic in certbot.compat.misc

* Add doc

* Fix lint

* Correct mypy

* Update client.py

certbot-nginx/certbot_nginx/configurator.py

@@ -12,24 +12,22 @@ import zope.interface
 
 from acme import challenges
 from acme import crypto_util as acme_crypto_util
+from acme.magic_typing import List, Dict, Set  # pylint: disable=unused-import, no-name-in-module
 
-from certbot import compat
 from certbot import constants as core_constants
 from certbot import crypto_util
 from certbot import errors
 from certbot import interfaces
 from certbot import util
-
+from certbot.compat import misc
 from certbot.plugins import common
 
 from certbot_nginx import constants
 from certbot_nginx import display_ops
-from certbot_nginx import nginxparser
-from certbot_nginx import parser
 from certbot_nginx import http_01
-from certbot_nginx import obj # pylint: disable=unused-import
-from acme.magic_typing import List, Dict, Set # pylint: disable=unused-import, no-name-in-module
-
+from certbot_nginx import nginxparser
+from certbot_nginx import obj  # pylint: disable=unused-import
+from certbot_nginx import parser
 
 NAME_RANK = 0
 START_WILDCARD_RANK = 1
@@ -895,7 +893,7 @@ class NginxConfigurator(common.Installer):
         have permissions of root.
 
         """
-        uid = compat.os_geteuid()
+        uid = misc.os_geteuid()
         util.make_or_verify_dir(
             self.config.work_dir, core_constants.CONFIG_DIRS_MODE, uid)
         util.make_or_verify_dir(