Rosetta Stone Project

Support specifying node class in src/frontend/model-builder.lisp

refs #1316

• src/frontend/model-builder.lisp (define-make-node): allow specifying
  ignored keyword parameters; accept and process class keyword
  parameter
  (define-make-node :enum): added accepted but ignore parameter qname
  of type `name/absolute'
  (define-make-node :structure): likewise
  (define-make-node :package): likewise
• test/frontend/model-builder.lisp
  (mock-structure-subclass): new class; mock structure class for
  builder test
  (test model-builder-root::smoke): explicitly specify node classes in
  some cases; query constructed repository/package to minimally verify
  correctness