All "result" types should take an IEnumerable<T> as input instead of List<T>.

[egil]

This spec:

openapi: 3.0.0
paths:
  /:
    get:
      summary: Get
      description: Get
      operationId: get
      tags: []
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                type: array
                items:
                  type: string

should result in the following C# (namespace and preamble excluded for brevity):

public class GetResult : ResultBase
{
    private GetResult(ActionResult result) : base(result) { }

    /// <summary>
    /// 200 - Ok response.
    /// </summary>
    public static GetResult Ok(IEnumerable<string> response)
        => new GetResult(new OkObjectResult(response ?? Enumerable.Empty<string>()));
}

I am considering removing the implicit conversion method, since C# doesnt allow implicit conversion from an interface to a concrete type. The alternative is to keep it, but define it as List<T>, e.g.:

public class GetResult : ResultBase
{
    private GetResult(ActionResult result) : base(result) { }

    /// <summary>
    /// 200 - Ok response.
    /// </summary>
    public static GetResult Ok(IEnumerable<string> response)
        => new GetResult(new OkObjectResult(response ?? Enumerable.Empty<string>()));

    /// <summary>
    /// Performs an implicit conversion from GetResult to ActionResult.
    /// </summary>
    public static implicit operator GetResult(List<string> response)
        => Ok(response);
}

Part of #93.