Java 14: add isRecord relation to dbscheme

Author: yo-h

java/ql/src/config/semmlecode.dbscheme

@@ -268,6 +268,10 @@ classes(
   int sourceid: @class ref
 );
 
+isRecord(
+  unique int id: @class ref
+);
+
 interfaces(
   unique int id: @interface,
   string nodeName: string ref,