Support required fields

[ejball]

At minimum, we could make the fields not optional in TypeScript. Ideally we would support validation akin to FacilityCSharp.

[heymb]

Ideally we would support validation akin to FacilityCSharp.

To clarify, does this mean implementing what the docs section "Field Validation" describe? I think DTOs are written for TS without any such validation like this.

[ejball]

Yes, that's what I mean.