Draft: Extract integrations out of Project class

What does this MR do and why?

It's just some throw away refactoring that we could reimplement properly. I think Project is overloaded of responsibilities and we should ideally have it stripped to its core and have other domains referencing it through project_id with behavior implemented in each domain.

Today it's more like this:

flowchart LR
 
p[Project] --> i[Integrations]
p --> c[Ci]
p --> mr[MergeRequests]
p --> r[Repositories]

Instead a better way would be:

flowchart LR

Integrations --> Project
Ci --> Project
MergeRequests --> Project
Repositories --> Project

This MR attempts to move part of the integrations behavior into Integrations:: domain.

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