Add requirements into pyproject.toml & Refactor anomalib install get_requirements

[harimkang]

📝 Description

To fix pypi install not properly finding requirements inside packages, move the list of requirements to pyproject.toml so that it has the package's metadata, and modify it to use this metadata to gather information from anomalib install.

• Move the list of requirements to pyproject.toml
• Modify the way anomalib install to use package's metadata requirements

✨ Changes

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• 🐞 Bug fix (non-breaking change which fixes an issue)
• 🔨 Refactor (non-breaking change which refactors the code base)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔒 Security update

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[ashwinvaidya17]

Thanks! I'd also be in favour of removing all the requirements.txt files but if that's going to be a big PR we can do it later