Respect ProblemDetailsService in default model validation filter

[captainsafia]

Gathered from #46349 (comment) and #46349 (comment).

We need to figure out a way to get the ValidationEndpointFilterFactory implementation to plug-in to the ProblemDetailsService so that it can respect global ProblemDetails-related configuration provided by the user.

This is usually supported via TypedResults but since there are circular dependencies issues we might just need to interact with the ProblemDetails service directly.

[marcominerva]

@captainsafia, I would like to help with this task, so I'm digging into the ValidationEndpointFilterFactory implementation:

aspnetcore/src/Http/Routing/src/ValidationEndpointFilterFactory.cs

Lines 62 to 67 in 3e4694b

	if (validatableContext.ValidationErrors is { Count: > 0 })
	{
	context.HttpContext.Response.StatusCode = StatusCodes.Status400BadRequest;
	context.HttpContext.Response.ContentType = "application/problem+json";
	return await ValueTask.FromResult(new HttpValidationProblemDetails(validatableContext.ValidationErrors));
	}

In this code block, getting the IProblemDetailsService from DI should be straightforward. But since the method needs to return a value, I ended up writing something like this:

if (validatableContext.ValidationErrors is { Count: > 0 })
{
    context.HttpContext.Response.StatusCode = StatusCodes.Status400BadRequest;

    var problemDetails = new HttpValidationProblemDetails(validatableContext.ValidationErrors);
    var problemDetailsService = context.HttpContext.RequestServices.GetService<IProblemDetailsService>();

    if (problemDetailsService is not null)
    {
        if (await problemDetailsService.TryWriteAsync(new()
        {
            HttpContext = context.HttpContext,
            ProblemDetails = problemDetails
        }))
        {
            // We need to prevent further execution.
            return await ValueTask.FromResult(EmptyHttpResult.Instance);
        }
    }

    // Fallback to the default implementation
    context.HttpContext.Response.ContentType = MediaTypeNames.Application.ProblemJson;
    return await ValueTask.FromResult(problemDetails);
}

Before creating a PR, I’d like to know if you think this is the right solution. Do you have any suggestions for improving it?