fix(kit): don't mutate existing component entries when overriding

[danielroe]

🔗 Linked issue

resolves #25787

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Previously, using Object.assign, we were mutating other components added with addComponent, when overriding with a higher priority component. This change ensures that we just swap our new component into the components array rather than mutating any existing data.

📝 Checklist

• I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.

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