Foundations-Object Basics: Add reading on deep & shallow copies

[tman2747]

Because

It would be helpful to introduce the concepts of shallow copy and deep copy before the fourth assignment in this chapter, particularly the palindrome assignment. Some learners may attempt to clean an array and then assign it to a new variable before calling .reverse() on it. Not realizing that .reverse() mutates the original array.

This PR

• Adds a reading assignment for two MDN chapters:
  • One on shallow copying of objects and arrays
  • One on deep copying techniques
• Aims to reduce confusion and improve learning flow during the palindrome assignment

Issue

Closes ##28597

Additional Information

• This could just as well be added to the additional resources section but I thought It was appropriate here.
• This is my first time doing a PR so if anything needs changed or fixed I'd be happy to do it :)

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
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• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
• If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• If any lesson files are included in this PR, they follow the Layout Style Guide

[rlmoser99]

While I understand the reasoning for wanting to include this in the lesson, I am of the viewpoint that the concept of shallow and hard copy is one that is good for the learner to stumble upon themselves. It is a great exercise to see behavior that you are not expecting and learn how to find the solution for yourself.

I'd love to know what @codyloyd thinks, before I speak for the team.