Implement CMS Integration service in the Shared SPA SDK

Follow specifications from the technical design document: https://docs.google.com/document/d/1AYu1d5IsA4xPtmUM9wmaQnhDamTP9TPn4ZT_daFGn7M/edit#heading=h.he0mmbs0gdxz

Requirements:

• Declare types for window SPA object.
• The flow from the Channel Manager to the SDK should be event-driven, so we can have full isolation in the user components.
• The code of the shared library should be strictly typed.
• The code should follow SOLID principles.
• Objects produced by the SDK should be immutable, so we can avoid side-effects in state management (clone properties object before triggering `render-component` event).
• All publicly available functions of the SDK should be pure, so a user will be able to extend the SDK on his end.
• The code should be covered by unit tests.