Add RequestsWrapper option to support UTF-8 for basic auth

[ofek]

Motivation

Part 1 of solution to #7176

[codecov]

Codecov Report

Merging #7441 into master will decrease coverage by 0.63%.
The diff coverage is n/a.

Impacted Files	Coverage Δ
disk/tests/common.py	64.28% <0.00%> (-35.72%)	⬇️
disk/tests/conftest.py	85.71% <0.00%> (-11.43%)	⬇️
disk/datadog_checks/disk/disk.py	83.66% <0.00%> (-3.59%)	⬇️
disk/tests/test_filter.py	96.45% <0.00%> (-3.55%)	⬇️
gitlab/tests/conftest.py
ignite/datadog_checks/ignite/__init__.py
kubelet/datadog_checks/kubelet/__about__.py
nginx/tests/test_vts.py
tomcat/datadog_checks/tomcat/__about__.py
mapr/datadog_checks/mapr/mapr.py
... and 740 more

[FlorianVeaux]

This is quite a big change for our integrations which could cause issues.
If a server only supports iso-8859-1/latin1 and not utf8, our integrations will suddenly stop working.
The question of "how many servers" are used that only support latin-1 is a difficult one.

We also know from issue #7176 that RabbitMQ only supports utf-8
Also utf-8 has been the default in browser for some time: https://developer.mozilla.org/en-US/docs/Web/HTTP/Authentication#Character_encoding_of_HTTP_authentication