Add testing for stale @jls and @jvms tags

The section names and numbers in JLS and JVMS are *mostly* stable, but change occasionally. When the names or numbers change, cross-references from the API docs using @jls and @jvms tag may have incorrect titles or point to incorrect sections.

A test based a stored index of JLS and JVMS section that was updated periodically could help catch when tags get out of date (see JDK-8257799).