ref(server): Organize project services in nested modules

[Dav1dde]

Organizing all the project_*.rs files we have in the services/ module in a module structure.

projects
├── cache.rs // <- services/project_cache.rs
├── mod.rs
├── project
│   ├── mod.rs // <- services/project.rs
│   └── state // <- services/project/state/*
│       ├── fetch_state.rs
│       ├── info.rs
│       └── mod.rs
└── source
    ├── local.rs // <- services/project_local.rs
    ├── mod.rs
    ├── redis.rs // <- services/project_redis.rs
    └── upstream.rs // <- services/project_upstream.rs

This only moves files around, no functional changes. It is a preparation to split out more of the convoluted services into smaller digestible parts. For example, the project_cache.rs module contains a lot of utility and helper types not relevant for the service itself, it should be possible to split this out eventually.

I chose projects as the base module to avoid having a project/project/ module, also I think it makes sense, it manages all projects and the nested module just represents a single project.

#skip-changelog