* [24] Check if preview flag is set in classfiles where needed

+ unify verifyClassFile methods
+ sprinkle actual checks into a few current preview test classes

* [24] Check if preview flag is set in classfiles where needed

+ set the flag only when preview is USED
+ record preview-use upon 'requires transitive java.base'

* [24] Check if preview flag is set in classfiles where needed

+ set the flag only when preview is USED -- really
+ improve detection for use of PRIMITIVES_IN_PATTERNS
+ FIXME in PrimitiveInPatternsTestSH, bypassing the new check

* Fix BatchCompiler2
+ expect preview version only when used
+ remove duplicate test

* + Evaluate usesPreview also when generating module-info.class
+ verify preview in class file for all conforming module import tests