[DX] AsyncMessaging: refactor existing class, usages and assets

[cuserox]

📚 Context

Before replacing the current asynchronous messaging setup, we could get it in a more decoupled state by improving areas of the existing code. Precedent to: #2743

🛠 Acceptance Criteria

Centered effort around the class instantiating the channel setup AsyncMessageChannel

Some improvement ideas:

• Use different methods to postMessages from figma.ui vs parent
• isInFigmaSandbox needs a better name
• Include error handling for prod / dev (including Sentry if necessary)
• Group all types in the same files and area of the project
• attachMessageListener can be further split out and tested