chore: create interface for pkgs to return codersdk errors (#18719)

This interface allows it to create rich codersdk errors and pass them up to the `wsbuilder` error handling.

coderd/httpapi/httperror/responserror.go

@@ -0,0 +1,19 @@
+package httperror
+
+import (
+	"errors"
+
+	"github.com/coder/coder/v2/codersdk"
+)
+
+type Responder interface {
+	Response() (int, codersdk.Response)
+}
+
+func IsResponder(err error) (Responder, bool) {
+	var responseErr Responder
+	if errors.As(err, &responseErr) {
+		return responseErr, true
+	}
+	return nil, false
+}