feat: add stylus template

[yahsan2]

Summary

Proposed changes

This PR brings the following changes:

• Add support for generating .styl (stylus) files;
• Add a default .stly (stylus) template;
• Add a demo .styl (stylus) file.

No dependencies were added or removed

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Testing

• I have added or updated tests that prove my fix is effective or that my feature works (if applicable)

How to test

1. Checkout the branch;
2. Run npm install;
3. Run npm run build && node dist/cli.js './src/__tests__/fixtures/svg-icons/*.svg' -d demo -t styl --normalize --center-horizontally;
4. Check if exit error is 0 (success);
5. Check if demo/webfont.styl file was created.

Test configuration

• Node.js version: v12.17.0;
• NPM version: 6.14.4.

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Checklist

• I have added corresponding labels to this PR (like bug, enhancement...);
• My commits follow the Conventional Commits 1.0 Guidelines;
• My code follows the style guidelines of this project;
• I have performed a self-review of my own code;
• I have mapped technical debts found on my changes;
• I have made corresponding changes to the documentation at 588a753;
• My changes generate no new warnings or errors;

[alexander-akait]

Thanks!

[jimmyandrade]

@yahsan2 thanks for contributing

[jimmyandrade]

Reviewed and merged

[yahsan2]

thank you for merging.