Move source-transform out of the ee-9 tree

The source-transform tree doesn't belong under ee-9 any more. Even if we rename 'ee-9' to 'preview' it doesn't belong.

Main hassle here is moving up a level to the source root will require updating the path to the javax source in all the child modules.

NOTE: Before doing any work on this there needs to be a discussion of how this relates to any plans for getting rid of source-transform altogether. I don't think anything on this issue should be done (even the discussion) until after WF 27 Beta.