- fix UnusedCodeFixCore.RemoveCastOperation and
  UnusedCodeFixCore.RemoveAllCastsOperation to look if the cast
  is part of an assignment where the left operand is the same as
  the operand being cast and in such a case, remove the entire
  statement
- add new tests to LocalCorrectionsQuickFixTest and CleanUpTest

Change-Id: Ic5ced8400f45226578484d7dc202ad7658604621
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.ui/+/191803
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Tested-by: Jeff Johnston <jjohnstn@redhat.com>
Reviewed-by: Jeff Johnston <jjohnstn@redhat.com>