fdo#74424 Use Window::GetOutDev() to access ImplInitFontList()

Part of the decoupling of Window from OutputDevice. We now get
the Window's OutputDevice instance and manipulate this. Do not rely
on the inherited function.

Change-Id: I18a2688d85ed23a4773e6527bd4923f7d6c83a28
Reviewed-on: https://gerrit.libreoffice.org/7799
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>