Is your feature request related to an existing module?
Currently, clicking the "Reject User" button in the user_accounts module instantly fires an AJAX request without any warning or confirmation. This can easily lead to accidental user rejections, which can be frustrating for project administrators.

Describe the solution you'd like
To wrap the rejection AJAX call inside a swal.fire() (SweetAlert2) confirmation modal, forcing the admin to explicitly confirm before the user is rejected.

Describe alternatives you've considered
Using a standard browser confirm() prompt, but LORIS standardizes on SweetAlert2 for modern UI components.

Additional context
To implement this cleanly without adding global script tags, rejectUser.js needs to be rewritten from a plain jQuery script into a compiled React/JSX file so that sweetalert2 can be cleanly imported via Webpack.