fix apq status

[vvakame]

I don't have good solutions... 🤔

so, APQ works in CreateOperationContext method.
and handler exec w.WriteHeader(http.StatusUnprocessableEntity) when its returns error.
but It's unexpected behavior in client.

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs)

[vvakame]

It doesn't seems right to always return 200... 🤔

[vvakame]

We needs some status code modifying process from middleware...
I'll try to implement it.

[vektah]

Sorry its taken so long to get back to this, went on holiday 🍹.

Maybe its best to keep it simple? We dont need to reimplement error presenter, just a way for handlers during early request processing to set the status code right?

what about

interface HttpStatusCoder {
   error
   HttpStatusCode() int
}

?