When building with RelWithDebInfo. The CMake code is adapted from
corresponding (internal) functions from Qt 6.
Also let the scripts create an additional *-debug.7z with the debug
info.
Task-number: QTCREATORBUG-24916
Change-Id: Ibc3c8c0013718b9c5e868136e5ce01e1e99f84c4
Reviewed-by: Cristian Adam <cristian.adam@qt.io>