Implement type definitions

[Pyrolistical]

Problem

Type definitions are not supported. https://github.com/WebAssembly/module-linking/blob/main/design/proposals/module-linking/Explainer.md#type-definitions

Without this feature, the purpose of this project would be violated. Users trying to learn how Module linking works would face difficulties.

Ideals

1. Config should not require any changes
2. Runtime should not require any changes

Acceptance criteria

1. Tests that prove type definitions are working
2. New demo example that uses type definitions