Fix displayName labelField to displayName to comply with API/table output

Output casing of Displayname does not match front-ends expectations. Other template labelFields have similar casing deviations from standard, so changing this to follow suit.

Author: MWGMorningwood

src/data/standards.json

@@ -3030,7 +3030,7 @@
         "label": "Select Group Template",
         "api": {
           "url": "/api/ListGroupTemplates",
-          "labelField": "displayName",
+          "labelField": "Displayname",
           "valueField": "GUID",
           "queryKey": "ListGroupTemplates"
         }