Feature: Setup the foundations for events, subscription and unsubscription

[mf366-dev]

The Vision

Well, we need a way for plugins to register what they listen to and what events they offer (private, protected and shared contexts).

The Problem

Well, the lack of an event registry, of course :)

The Solution

Essentially, there would be a registry for plugins to register what they want to listen to, whether it's internal editor events or events coming from other plugins.

User Impact

Literally everyone making plugins.

[mf366-dev]

With this issue, we also begin working on the plugin SDK itself and everything revolving it.