JSON Serializer for pystencils config

This MR adds a custom JSON serializer to allow pystencils configs to be used as parameters in databases. Useful in parameter studies when using the more modern way of setting up simulations, i.e., using pystencils' CreateKernelConfig.

Can be extended in the future for other custom classes if needed.

pystencils/runhelper/db.py

@@ -9,7 +9,7 @@ from blitzdb.backends.file.backend import serializer_classes
 from blitzdb.backends.file.utils import JsonEncoder
 
 from pystencils.cpu.cpujit import get_compiler_config
-from pystencils import CreateKernelConfig, Target, Backend
+from pystencils import CreateKernelConfig, Target, Backend, Field
 
 import json
 import sympy as sp
@@ -30,6 +30,10 @@ class PystencilsJsonEncoder(JsonEncoder):
             return str(obj)
         if isinstance(obj, (Target, Backend, sp.Symbol)):
             return obj.name
+        if isinstance(obj, Field):
+            return f"pystencils.Field(name = {obj.name}, field_type = {obj.field_type.name}, " \
+                   f"dtype = {str(obj.dtype)}, layout = {obj.layout}, shape = {obj.shape}, " \
+                   f"strides = {obj.strides})"
         return JsonEncoder.default(self, obj)