[Issue] Fixed media folder symlinks

[m2-assistant]

This issue is automatically created based on existing pull request: #40837: Fixed media folder symlinks

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Description (*)

The new validation gives errors when a situation uses atomic deployments where the media folder is set as a shared folder.

Given some debugging, we can see that the $quoteResolved path resolves the symlink:
/home/www/example.com/shared/pub/media/custom_options/quote

While the $mediaDirectory->getAbsolutePath() does not resolve symlinks:
/home/www/example.com/releases/000/pub/media/

By wrapping it in realPath we force it to resolve those symlinks and we end up comparing
/home/www/example.com/shared/pub/media/custom_options/quote to /home/www/example.com/shared/pub/media/ which is what we want to see in situations with a symlink

Manual testing scenarios (*)

1. Make a symlink from pub/media to somewhere else (e.g. even an external disk)
2. Attempt to add a product option file to your cart
3. See how the Invalid file path. error gets throw.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)

[github-jira-sync-bot]

✅ Jira issue https://jira.corp.adobe.com/browse/AC-17280 is successfully created for this GitHub issue.