Adding czds.py script

[jpleger]

This is a much simpler and more pythonic implementation of the example client.

Some things that are different from the example Python implementation:

1. The core functionality is implemented as a class that can be used in other code.
2. Authentication is lazy (won't be ran until needed)
3. Authentication headers can be accessed by the CZDSClient.auth_headers property.
4. Errors are handled via exceptions
5. Filenames are based off URLs, not returned response from server (this could easily be changed, but was a design decision)
6. Credentials are provided via config options or env variables (helps with automation)

If desired, I can wire this up to a CI pipeline and add a setup script so this can be distributed via PyPi, and users can just pip install it.