Allow local interfaces

Java 16 permits enums and interfaces to be declared method-locally. Enums are already classes, but interfaces are not (in dbscheme terms), so we need to permit isLocalClass to tag them like it already does classes.

Author: smowton

java/ql/lib/config/semmlecode.dbscheme

@@ -442,7 +442,7 @@ isAnonymClass(
 
 #keyset[classid] #keyset[parent]
 isLocalClass(
-  int classid: @class ref,
+  int classid: @classorinterface ref,
   int parent: @localclassdeclstmt ref
 );