[pp-3] Convert hook_requirements to new classes or hook_runtime_requirements

For scope, wondering if we really need separate issues for all of these. E.g. the one for update (status) will be a simple move to an OOP hook_runtime_requirements(). Maybe we should group by all modules that only implement a single phase in their hook_requirements()?

• Only needs hook_runtime_requirements()
• Only needs hook_update_requirements()
• Only needs the hook_install_requirements() class
• Separate issues for each module that implements more than 1 phase

I can't wait to see system_requirements() refactored. That's going to help so much. I might even be inspired to raise my hand to at least start on that one. ;)

Opened 📌 [pp-3] Split up and refactor system_requirements() into OOP hooks Active to track it. Adding to summary.

Yeah that split was my real plan, glad to see some momentum here!