fix(plugin-redirects): make 'from' field unique to prevent errors in redirect logic

[jessrynkar]

What?

This PR updates the from field in plugin-redirects to add unique: true.

Why?

If you create multiple redirects with the same from URL — the application won't know which one to follow, which causes errors and unpredictable behavior.

How?

Adds unique: true to the plugin injected from field.

Migration Required

This change will require a migration. Projects already using this plugin will need to:

• Ensure there are no duplicate from values in their existing redirects collection.
• Remove or modify any duplicate entries before applying this update.

Fixes #12959

[DanRibbens]

Adding unique to a field will require a migration. I think it is fine as long as we document it in the PR description and then also we will need to edit the release notes to include the extra instruction also.

If a project already has non-unique records, duplicates will need to be updated prior to adding the unique constraint.

[github-actions]

🚀 This is included in version v3.46.0