COMP: Reduce number of copy/compile python targets

Set variable CTK_COMPILE_PYTHON_SCRIPTS_GLOBAL_TARGET_NAME
to "Slicer" to create targets:
CopySlicerPythonResourceFiles
CopySlicerPythonScriptFiles
CompileSlicerPythonFiles

Before this commit, for each set of script processed directly or
indirectly by the macro "ctkMacroCompilePythonScript", two targets
are created. For example:

[...]
CopyAAAPythonFiles
CopyAAAPythonResourceFiles
CompileAAAPythonFiles
[...]
CopyBBBPythonFiles
CopyBBBPythonResourceFiles
CompileBBBPythonFiles
[...]
CopyCCCPythonFiles
CompileCCCPythonFiles
[...]

After integrating the commit, independently of the number
of set of scripts, within Slicer core the following three
targets will be available:

CopySlicerPythonResourceFiles [If there are python resources]
CopySlicerPythonScriptFiles
CompileSlicerPythonFiles

Note that this will apply only for Slicer core, by default,
if an extension bundles 2 scripted modules, the following targets
will be available:

CopyModule1PythonScriptFiles
CompileModule1PythonFiles

CopyModule2PythonResourceFiles
CopyModule2PythonScriptFiles
CompileModule2PythonFiles

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22041 3bd1e089-480b-0410-8dfb-8563597acbee