BUG: Fix/improve launcher path setup

Take advantage of recent changes in the CTK AppLauncher to use the list
form of setting up additional environment path lists. Particularly, we
now declare as path lists those environment variables that are (i.e.
QT_PLUGIN_PATH, PYTHONPATH) so that we no longer lose the user's paths
that have been set in these.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23036 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fix creation of launcher configuration

Remove hack to delete the launcher configuration as part of the build.
The launcher CMake helpers should now be producing correct dependency
information such that the hack is unnecessary, and the dependencies for
the hack were not set up correctly, causing ninja builds to fail to
recreate the configuration on alternating runs (which would prevent
slicer from running).

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23037 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fix/rewrite setupSlicerEnvironment.sh

Rewrite setupSlicerEnvironment.sh to use the new launcher option to
generate commands to set the environment. This fixes several problems
with the old setupSlicerEnvironment.sh, including:

- Failure to properly quote in order to cope with special characters.
- Incorrectly treating everything as a path list.

The new script is a glorified wrapper around 'eval' and exists more for
backwards compatibility than anything (and also now states that it is
deprecated).

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23038 3bd1e089-480b-0410-8dfb-8563597acbee