- fix RemoveUnusedMemberOperation.removeVariableWithInitializer() in
  UnusedCodeFixCore to check if right-hand is a field access in which
  case remove the field accesses so a valid expression statement
  can be created
- add new test to CleanUpTest

Change-Id: I25ca80e8b3a952ff21ace9303717966f070fdbd0
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.ui/+/189578
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Tested-by: Jeff Johnston <jjohnstn@redhat.com>
Reviewed-by: Jeff Johnston <jjohnstn@redhat.com>