bugfix for base64 encoded arguments

[arielkr256]

Background

is_base64 was generating some false positives for non-base64 strings

Changes

• added validate=True to b64decode check to ensure decoded strings are not garbled https://stackoverflow.com/questions/2941995/python-ignore-incorrect-padding-error-when-base64-decoding
• split command line arguments on quotes, '=', and spaces to account for quoted and prefixed base64 command line strings
• added 3 new test cases

Testing

• make test

[github-actions]

😱
looks like some things could be wrong with the packs

[INFO][root]: ignoring file dependabot.yml

[ben-githubs]

LGTM!