Request: Shared state for ArchConfigHandler to allow configuration overrides

[ScarletEmanu]

describe the request

Currently, each instance of the class ArchConfigHandler instantiates and reads configuration files independently. This behavior prevents plugins or external hooks from modifying the configurations processed by the guided installer in real-time. Is it possible to implement this class as a singleton or inject the instance of the handler into the installer instance so that modifications are persisted across the installation lifecycle?

I'm open to submitting a PR if we can agree on the architectural direction (Singleton vs Injection).

[h8d13]

This is already being done in #4149 and has many more call-sites up for conversion ! Go for it :)