Make BCEL classpath utility recognise Java 16-19, fixing many tests

Make BCEL classpath utility recognise Java 16-19, fixing many tests

This is a follow-up commit on @07af5d41:
Inside org.aspectj.apache.bcel.util.ClassPath.getClassPath(), some JVM
version matching occurs which previously did not include Java 16 (I also
added 17-19 to the regex matcher). This fixes test errors like:

java.lang.ClassCastException:
  class org.aspectj.weaver.MissingResolvedTypeWithKnownSignature
  cannot be cast to class
  org.aspectj.weaver.ReferenceType
  (org.aspectj.weaver.MissingResolvedTypeWithKnownSignature and
  org.aspectj.weaver.ReferenceType are in unnamed module
  of loader 'app')

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>