BUG: Extension build system: Ignore extension CTest return code. Fixes 0004247

This commit ensures each "EXTENSION_UPLOAD_COMMAND" responsible to configure,
build, test and package any given extension is completely "sandboxed" by
using a wrapper script.

This is required because simply setting the RETURN_VALUE parameter
to the ctest_test() command is not enough to avoid the script from
exiting with error code.

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The following wrapper script is required to workaround issue 0004247

and avoid the all extension build from failing if a test of

extension fail.

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Note that as soon as CMake >= 3.6.7 is released, it should be possible

to remove the wrapper script and simply specify CAPTURE_CMAKE_ERROR

ctest_test option.

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See https://cmake.org/cmake/help/v3.7/command/ctest_test.html

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Tested-by: Isaiah Norton <inorton@bwh.harvard.edu>
Tested-by: Johan Andruejol <johan.andruejol@kitware.com>
Tested-by: Nicole Aucoin <nicole@bwh.harvard.edu>
Tested-by: Steve Pieper <pieper@isomics.com>

Reported-by: Csaba Pinter <csaba.pinter@queensu.ca>
Reported-by: Andras Lasso <lasso@cs.queensu.ca>

Thanks: All of the above

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25439 3bd1e089-480b-0410-8dfb-8563597acbee