Debugger: Add some convenience to display "paired" data

The switch between compact/full display was so far part of the
individual dumpers, there's some potential for code-reuse here.

Change-Id: I47e3308cfd2209948adbf70fca617908e793c0fc
Reviewed-by: hjk <hjk121@nokiamail.com>
Debugger: Fix QDir dumper after QtBase change 9fc0965d19

Change-Id: Ibbef8ec7427e8b021c830de3a668bf82fe3511da
Reviewed-by: hjk <hjk121@nokiamail.com>