feat(api): add List Strings on Workflow Step method

[imprvhub]

This commit implements API endpoint to list strings on workflow steps with full test coverage:

• Add list_workflow_step_strings method with query parameters support
• Implement path helper get_workflow_step_strings_path
• Add parameterized tests covering basic usage, full parameters and edge cases
• Add mock tests for API request validation
• Ensure all test cases follow existing patterns in the codebase
• Follow Crowdin Enterprise API specification

Closes #184

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.21%. Comparing base (1fa4b5b) to head (f84ded2).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #186      +/-   ##
==========================================
+ Coverage   99.21%   99.21%   +0.01%     
==========================================
  Files         166      166              
  Lines        6505     6519      +14     
  Branches      149      149              
==========================================
+ Hits         6453     6467      +14     
  Misses         36       36              
  Partials       16       16              

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[imprvhub]

@andrii-bodnar I removed those whitespace lines specifically because they were causing flake8 validation errors. The linter was reporting W293 (blank line contains whitespace) on lines 40, 74, and 91. By removing these whitespaces, we ensure the code passes all quality checks while maintaining functionality. This change was not arbitrary but necessary for code quality compliance.

[andrii-bodnar]

@imprvhub hmm, it's interesting why it didn't fail before. Probably the rules have changed over time and it only fails on updated files or something. Ok, let's make it follow the validation rules.

[imprvhub]

@andrii-bodnar Done!.

[andrii-bodnar]

@imprvhub thank you for the contribution!