Refactor ModuleListForm

Problem/Motivation

Module list form does some dependency calculations to ascertain whether to disable the checkbox for enabling a module.

To pave the way for #3005229: Provide optional support for using composer.json for dependency metadata → we should refactor it a bit.

Proposed resolution

At the moment we have a hunk with an if/elseif/elseif/elseif/else ie that's three elseifs.
Once we get to #3005229: Provide optional support for using composer.json for dependency metadata → we'll need another for the different path between the composer and BC layer. One elseif is too many, and four is just plain ugmo.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet