Protected packages: Add regex validation for pypi protection rules

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What does this MR do and why?

Protected packages: Add regex validation for pypi protection rules

• Add regex validation for PyPi package name pattern in protection rules Changelog: added

🛠️ with ❤️ at Siemens

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

MR Checklist (@gerardo-navarro)

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the javascript style guides
• Conforms to the database guides

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable the feature flag packages_protected_packages_pypi via the rails console

Feature.enable('packages_protected_packages_pypi')

2. Go to Settings => Packages and Registries : http://gdk.test:3000/flightjs/Flight/-/settings/packages_and_registries
3. Try to add a package protection rule for a pypi package with an examplary package name pattern @my-scope/my-package-with-regex-characters.+ => 💥 You should see an error as shown in the screenshot