BUG: only time out extra storable message during testing

The pop up window that gives the user feedback about how
not to lose new storable data after creating a scene view
was timing out before some testers could finish reading
and understanding the information. Added a boolean property
to the capture tool bar, popupsTimeOut, that the main
window can set to true when the enable testing attribute
has been turned on. Verified that the test
AddStorableDataAfterSceneViewTest
still passes and doesn't hang.

Issue 0003956

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24397 3bd1e089-480b-0410-8dfb-8563597acbee