Files included by hook_hook_info groups will be deprecated

Problem/Motivation

📌 Deprecate hook_hook_info() Active

Crucially we cannot deprecate hook_hook_info itself in a BC way.
If we did then modules implementing it would remove the hook and any modules relying on the auto include functionality would no longer work and sites would break.

Instead we do a 'soft' deprecation where we send a notice to everyone relying on the functionality.
In order to do this here I think we need to invoke hook_hook_info then see if any $module.$group.inc files exist and move the contents to the .module file.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes