feat(dynamic-sections): add custom css classes option (#4256)

packages/translation/src/lang/en.json

@@ -1163,6 +1163,9 @@
         "title": {
           "label": "Title"
         },
+        "customCssClasses": {
+          "label": "Custom css classes"
+        },
         "borderColor": {
           "label": "Border color"
         }