Provide a way to update Composer from the UI

Problem/Motivation

We are going to ship a version of Composer with the cpanel template in order to ensure it meets the minimum required. ✨ Require Drupal 11.2.3 and add Composer as a runtime dependency Postponed

This means we also need to provide users with a way to update composer from the UI, so they can continue to use it if the constraint is updated.