Abandon use of Luau's typeof

[R-unic]

Currently a class' type is defined with just type ClassName = typeof(ClassName). This is turning out to have more issues than anticipated, so instead we will track every field/method, and emit an interface type for the class.

If we have

class Abc<T>
{
  public T Foo { get; }
}

Then the type emitted should be

type Abc<T> = {
  read Foo: T;
}