- add logic to VarCleanUp.maybeUseVar() to handle constructors,
  super method calls, and super constructor calls
- add new tests to CleanUpTest11

Change-Id: I9d01b4be6ddbf2b6a0710170840e888ddfd5db34
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.ui/+/180077
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Tested-by: Jeff Johnston <jjohnstn@redhat.com>
Reviewed-by: Jeff Johnston <jjohnstn@redhat.com>