MVP Refactor/Cleanup

[jakehemmerle]

Refactoring and documenting the major components of the MVP. Main reasons for this:

• Get users building on it as quick as possible (abstractions and instructions)
• Solid foundation for scaling develeopment (documentation)

Functional requirements:

• Share WIT file between projects
• Proper generation and export of WITs from ec-core
• Template compiles to component model (build.rs)
• Template for basic constraints (basic.rs)
• Refactor/cleanup ec-runtime API

What can be left for another ticket?:

• Wasm Component Registry Server (for WITs and for Components)
• User testing includes compiling + testing with ec-runtime (This doesn't need to be done until we have runtime APIs)
• Release optimizations