[Tests] Add unit tests for string utility functions

[gonzaloriestra]

Why are these changes needed?

This PR adds unit tests for string helper functions in packages/cli-kit/src/public/common/string.ts that previously lacked test coverage, including:

• capitalize
• slugify
• escapeRegExp
• camelize
• capitalizeWords
• hyphenate
• underscore
• constantize
• pascalize
• getRandomName('creative')
• joinWithAnd([])

How to test your changes?

CI

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PR created automatically by Jules for task 10028013695398611560 started by @gonzaloriestra

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