vendor: add github.com/koofr/go-koofrclient

* added koofr client SDK dep for koofr backend

vendor/github.com/koofr/go-httpclient/errors.go

@@ -0,0 +1,38 @@
+package httpclient
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+)
+
+type InvalidStatusError struct {
+	Expected []int
+	Got      int
+	Headers  http.Header
+	Content  string
+}
+
+func (e InvalidStatusError) Error() string {
+	return fmt.Sprintf("Invalid response status! Got %d, expected %d; headers: %s, content: %s", e.Got, e.Expected, e.Headers, e.Content)
+}
+
+func IsInvalidStatusError(err error) (invalidStatusError *InvalidStatusError, ok bool) {
+	if ise, ok := err.(InvalidStatusError); ok {
+		return &ise, true
+	} else if ise, ok := err.(*InvalidStatusError); ok {
+		return ise, true
+	} else {
+		return nil, false
+	}
+}
+
+func IsInvalidStatusCode(err error, statusCode int) bool {
+	if ise, ok := IsInvalidStatusError(err); ok {
+		return ise.Got == statusCode
+	} else {
+		return false
+	}
+}
+
+var RateLimitTimeoutError = errors.New("HTTPClient rate limit timeout")