Render computed fields as their base type

[sdboyer]

Currently, the following input:

Something: {
	foo: bool & bar == "someval"
	bar: string
} @cuetsy(kind="interface")

will be translated as follows:

export interface Something {
  foo: false; // this is the problem
  bar: string;
}

It's doing this because in non-concrete schema form, it's true that bar != "someval", even though it's still possible that a value could arrive later and make it true.

These kinds of computed fields are a very powerful use case for CUE, and we want to be able to use them in schema without messing up language codegen. It'd be great if cuetsy could be smart enough to figure this out on its own. Or, if there's too much ambiguity, we could consider introducing a hinting attribute like @cuetsy(asBase) to indicate to the analyzer that it should just render the TS type corresponding to the incomplete kind of the field.