feat: get image blob in backend (#495)

* feat: get image blob in backend

* chore: update

plugin/http_getter/util.go

@@ -0,0 +1,15 @@
+package getter
+
+import (
+	"mime"
+	"net/http"
+)
+
+func getMediatype(response *http.Response) (string, error) {
+	contentType := response.Header.Get("content-type")
+	mediatype, _, err := mime.ParseMediaType(contentType)
+	if err != nil {
+		return "", err
+	}
+	return mediatype, nil
+}