Foundations Text Editors lesson: Fix broken VSCode MacOS download link

[sameeksha-dalvi]

Because

The VSCode download link for MacOS in the Foundations Text Editors lesson is broken and returns a "Not Found" error.

This PR

• Replaces the broken MacOS VSCode download link with the stable Darwin universal version .zip link as suggested by the maintainer

Issue

Closes #30970

Additional Information

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• 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