Fix enum reference

[spinillos]

When we reference an enum value, cuetsy was setting only the enum class missing the value.

For example:

Enum: "value1" | "value2" @cuetsy(kind="enum")

MyClass: {
  value: Enum.Value1
} @cuetsy(kind="interface")

was generating:

export enum Enum {
  Value1 = "value1",
  Value2 = "value2",
}

export interface MyClass {
  value: Enum;
}

and now it generates:

export interface MyClass {
  value: Enum.Value1;
}

[sdboyer]

We explored doing this with the original approach to cuetsy - basically, having enums in CUE be structs - as that seemed most obviously comparable to the way that enums feel to folks writing TypeScript.

But it doesn't work out. The enum field names that we choose to generate in cuetsy do not exist in CUE; CUE (correctly) interprets Enum.Value1 as a reference, and that reference does not exist. Nor can it, because Enum is string-kinded, not struct-kinded.