Improve TypeScript typechecking

[lastmjs]

The Generator type in TypeScript cannot currently infer the return type from a yield expression based on the return type of the yield expression, which is causing issues. We really aren't able to have static typings on any async operations, so users will have to put them in themselves to be sure.

Follow these issues:

• Generator: infer the type of yield expression based on yielded value microsoft/TypeScript#32523
• 💡 Yield Overrides microsoft/TypeScript#43632

If TypeScript implements this functionality we should be good, but we should also consider creating our own VS Code plugin to add some Azle-specific types...for example, forcing the user to use the yield keyword if they are calling an async api

[lastmjs]

We don't use generators for asynchronous calls anymore