Add support for providing OpenApi documentation

[NxSoftware]

When using Immediate.Validations (IV) with Immediate.Apis (IA), or even vanilla Minimal APIs / MVC controllers, there is no support for populating OpenApi/Swagger documentation with the appropriate metadata based on validations defined using IV.

It feels appropriate that this should be a separate package, i.e. Immediate.Validations.OpenApi as not everyone will be using Microsoft.AspNetCore.OpenApi, which begs the question should there also be Immediate.Validations.Swashbuckle?

[viceroypenguin]

It feels appropriate that this should be a separate package

Shouldn't be necessary. Just need to identify if IA or aspnetcore is referenced (or maybe an assembly configuration) and decide whether to generate related necessary properties in the validated object.