Fix #5435: show permission denied message when 403 on collection mapper

[guillermo-escire]

References

Fixes #5435

Description

When a user without permission attempts to change a mapped collection, the UI now shows a clear "Permission denied" message instead of a generic error when the backend returns a 403 Forbidden response.

Instructions for Reviewers

List of changes in this PR:

• Added 403 status code check in showNotifications method in item-collection-mapper.component.ts to differentiate permission errors from other errors
• Added i18n keys for permission denied messages in en.json5 for both map and remove operations
• Added new specs to cover the 403 case in both mapCollections and removeMappings

How to test:

1. Log in as a user without permission to change a mapped collection
2. Navigate to an item → Administer → Collection Mapper
3. Attempt to map or remove a collection
4. Verify the error message now says "Permission denied" instead
   of a generic error message

Checklist

This checklist provides a reminder of what we are going to look for when reviewing your PR. You do not need to complete this checklist prior creating your PR (draft PRs are always welcome).
However, reviewers may request that you complete any actions in this list if you have not done so. If you are unsure about an item in the checklist, don't hesitate to ask. We're here to help!

• My PR is created against the main branch of code (unless it is a backport or is fixing an issue specific to an older branch).
• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes ESLint validation using npm run lint
• My PR doesn't introduce circular dependencies (verified via npm run check-circ-deps)
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• My PR aligns with Accessibility guidelines if it makes changes to the user interface.
• My PR uses i18n (internationalization) keys instead of hardcoded English text, to allow for translations.
• My PR includes details on how to test it. I've provided clear instructions to reviewers on how to successfully test this fix or feature.
• If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• If my PR fixes an issue ticket, I've linked them together.

[tdonohue]

👍 Thanks @guillermo-escire ! I tested and reviewed this today. The bug is fixed and the code looks good.

I also realized this same issue appears to exist in 9.x. So, I'm flagging this for automatic backport to 9.x to fix the issue there as well.

[dspace-bot]

Successfully created backport PR for dspace-9_x:

• [Port dspace-9_x] Fix #5435: show permission denied message when 403 on collection mapper #5486