Allow type generation of const enums

[schicks]

In most of my codebase I avoid real typescript enums so that we can use constant strings interchangeably with the enum values. While the runtime values of zeus enums are the same as my constant strings, the fact that they are generated as an enum rather than a const enum (or just a ts union) means that I get type errors when I try to provide the underlying values to something typed from zeus generation.

I'd like to be able to configure zeus to generate const enums or string unions, similar to how you can with graphql let. I was not able to find evidence of this in the documentation.

[schicks]

I did some code diving and it looks like this is possible, just not clearly documented?

[hyusetiawan]

@schicks were you able to make this work with string union?

[schicks]

Not exactly. The linked bit shows how to generate const enums, but that still has compatibility issues when compared to string unions or enums defined elsewhere. Some other way to do this, or another similar option to generate string unions, would be helpful.