fix: Update args parameter regex to allow optional whitespace after commas

[aviatco]

✨ Description of new changes

Fix #130
This pull request updates the argument-parameter parsing logic to better handle optional whitespace after commas, improving the robustness of parameter string parsing. It also adds comprehensive tests to validate this behavior and includes minor code cleanups.

Parameter parsing improvements:

• Updated the regex pattern in get_dict_from_params (in fab_util.py) to allow for optional whitespace (including spaces, tabs, and newlines) after commas, making parameter parsing more flexible and user-friendly.
• Added multiple test cases in test_get_dict_from_params to ensure the new regex correctly handles various whitespace scenarios after commas, including spaces, tabs, and mixed whitespace.

Documentation and metadata:

• Added a changelog entry describing the regex update for argument-parameter parsing. (.changes/unreleased/fixed-20260112-141104.yaml)