Credential Logging

[VikramJayanthi17]

This PR implements a basic version of credential logging as mentioned in the #381 checklist, . This is a draft PR as I was unsure of how we want to implement the specifics. This is how this functionality is described(by @bhrutledge) in the checklist:

How the credentials (username, password, certificates) are set (.pypirc, keyring, CLI) and what they are (w/ placeholders for sensitive values)

The questions I have are:

• I assumed that when a user inputs their username/password through the prompt, we do not need to log that it happened via the prompt. Do we want to log this?
• What does a "placeholder" look like here? What values are sensitive other than passwords?

Any feedback on this PR or answers to these questions would be greatly appreciated.

TODO:

• Add tests

[bhrutledge]

Good stuff! Nice job wading through the complexity of how the username and credentials are set. My requests are just to normalize the log messages.

For example:

$ twine upload --verbose -r testpypi --disable-progress-bar dist/*
Using configuration from /Users/brian/.pypirc
Uploading distributions to https://test.pypi.org/legacy/
  dist/example_pkg_bhrutledge-0.0.4a6-py3-none-any.whl (2.6 KB)
  dist/example-pkg-bhrutledge-0.0.4a6.tar.gz (1.3 KB)
username set from config file
password set from keyring
username: __token__
password: <hidden>
Uploading example_pkg_bhrutledge-0.0.4a6-py3-none-any.whl
Uploading example-pkg-bhrutledge-0.0.4a6.tar.gz

$ twine upload --verbose -r testpypi -u bhrutledge --disable-progress-bar dist/*
Using configuration from /Users/brian/.pypirc
Uploading distributions to https://test.pypi.org/legacy/
  dist/example_pkg_bhrutledge-0.0.4a6-py3-none-any.whl (2.6 KB)
  dist/example-pkg-bhrutledge-0.0.4a6.tar.gz (1.3 KB)
username set by command options
Enter your password: 
username: bhrutledge
password: <empty>
Uploading example_pkg_bhrutledge-0.0.4a6-py3-none-any.whl
...
HTTPError: 403 Forbidden from https://test.pypi.org/legacy/
Invalid or non-existent authentication information. See https://test.pypi.org/help/#invalid-auth for more information.

[bhrutledge]

@VikramJayanthi17 FYI, I've merged a handful of changes for unrelated failing tests on master; it'd be worth merging those into your branch.

[bhrutledge]

@VikramJayanthi17 FYI, I've merged some formatting changes that will likely cause a merge conflict on this PR.

[bhrutledge]

@di I haven't heard from @VikramJayanthi17 in awhile. Is it okay if I commit my suggestions and finish up this PR?

[di]

@bhrutledge Yes, his internship has ended and he's back at school now. I think it's probably fine for you to take over here.

[bhrutledge]

Finally got around to adding some tests, which uncovered a small UX tweak. I'm very happy to merge this. @VikramJayanthi17 thanks again for all of your work!