POC: refactor to be package-based

[gagik]

This is a complete refactor POC where server is split into monorepo package with single responsibility. This only does it for the core subset of the packages as a demonstration. As a side effect, it also includes the following changes

• UserConfig is completely decoupled from most dependencies - it currently acts like a global setting store but for library usage there's really no need for this to be a thing at all (at least not a required thing).
• Explicit dependency injection

This is quite rough around the edges but it already revealed some interesting things about our code, such as the fact that there are classes where we have included the entire userConfig to either not use at all later or just to check 1 single field.