QtIFW

Add .qt-license-check.exclude and .qt-license-check.optional rules

Installer-framework has two imported third party modules.

src/libs/7zip:
- Do not attempt to check for license headers for these files,
  use exclude filter.

src/libs/kdtools
- If license headers exist then check those i.e. optional.
  These files are contributed by KDAB.

Change-Id: Ie3c7507c0386680ae84987628291a9612590a4f7
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>