HTTPBasicAuth Feature

In CPython requests it looks like there is HTTPBasicAuth which handles encoding credentials into the appropriate format. https://requests.readthedocs.io/en/latest/user/authentication/ we could add that class in the adafruit_requests library and then have matching APIs between circuitpython and CPython more closely.

Once implemented this could be used to simplify a few of the examples that make use of basic auth.

This was originally discussed in #167

Start with the adafruit_requests library and compare its API with CPython requests.HTTPBasicAuth using the linked authentication documentation. Review the basic-auth examples and discussion in #167 to identify the matching API expected. Done means the library exposes the class and the relevant examples can use it to simplify basic authentication.

Written by the indexing model from the issue text.