Deprecate HttpStatusCodeHandlers.fs in favor if Minimal API IResult

[xperiandri]

I propose to add the function below to the Core.fs and deprecate HttpStatusCodeHandlers.fs

open Microsoft.AspNetCore.Http
open Giraffe

let result (res: IResult) : HttpHandler =
    fun (_: HttpFunc) (ctx: HttpContext) -> task {
        do! res.ExecuteAsync(ctx)
        return Some ctx
    }

Because:

1. Less stuff to support
2. Known to ASP.NET developer
3. More sophisticated
4. Easier to support OpenAPI metadata