feat: error_code + api doc + printing-job fields

flower/error_code_views.py

@@ -0,0 +1,12 @@
+from rest_framework.permissions import AllowAny
+from rest_framework.response import Response
+from rest_framework.views import APIView
+
+from flower.error_code_registry import list_error_code_groups
+
+
+class ErrorCodeListView(APIView):
+    permission_classes = [AllowAny]
+
+    def get(self, request):
+        return Response({'modules': list_error_code_groups()})