Fix: Add authorization checks for media deletion

[krishana7911]

Summary

Issue Resolved: https://github.com/rtCamp/rtmedia-io/issues/1900
This PR improves permission handling in the media deletion flow by adding proper authorization checks before allowing a media item to be deleted.

Changes

• Validate that the current user is authorized to delete the requested media

• Allow deletion only if the user is:

  • The owner of the media
  • A site administrator
  • A group administrator (for group media)

• Return an error response when an unauthorized deletion is attempted

Impact

• Prevents unintended deletion of media by users without appropriate permissions
• Ensures media deletion behavior aligns with expected access control rules

Testing

• Verified that users can delete their own media
• Verified that administrators can delete any media
• Verified that unauthorized users cannot delete media belonging to others

Notes

This change does not affect existing functionality for authorized users and maintains backward compatibility.

[rtBot]

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• app/main/controllers/template/rtmedia-ajax-actions.php

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