[Windows] Security model for files permissions - STEP 3c (#6967)

* Implement security.open

* Clean lint

* Rename security into filesystem

* Update certbot/compat/filesystem.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/util.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/lock.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/compat/os.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/lock.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/compat/os.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Simplify and make more clear comment on os.open.

* Secure implementation preventing race conditions

* Revert "Secure implementation preventing race conditions"

This reverts commit dbb8549219.

* Simplify the logic on Windows.

* Implement os.open to prevent race conditions

* Add unit tests

* Handle os.O_CREAT and os.O_EXCL directly from the Windows APIs

* Improve comments

* Use CREATE_ALWAYS

* Adapt coverage threshold to new Windows specific LOCs.

* Update certbot/compat/os.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/compat/os.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/compat/os.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/compat/filesystem.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Add some comments

* Fix pylint

* Improve docstring

* Added test cases

* Improve docstring

* Update certbot/lock.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Update certbot/lock.py

Co-Authored-By: ohemorange <ebportnoy@gmail.com>

* Fix lint

* Adapt coverage

* Adapt coverage

tox.cover.py

@@ -12,7 +12,7 @@ DEFAULT_PACKAGES = [
     'certbot_dns_sakuracloud', 'certbot_nginx', 'letshelp_certbot']
 
 COVER_THRESHOLDS = {
-    'certbot': {'linux': 97, 'windows': 96},
+    'certbot': {'linux': 96, 'windows': 96},
     'acme': {'linux': 100, 'windows': 99},
     'certbot_apache': {'linux': 100, 'windows': 100},
     'certbot_dns_cloudflare': {'linux': 98, 'windows': 98},