CPack: Deprecate OSXX11 and PackageMaker generators

The CPack OSXX11 generator has not had any updates since 2011 (commit 0fb388c7) except as part of sweeping maintenance changes. It also creates packages with a OSXScriptLauncher binary that has only ppc and i386 architectures which are not supported by Apple anymore:

$ git grep OSXScriptLauncher
Source/CMakeLists.txt:  add_executable(OSXScriptLauncher
Source/CMakeLists.txt:    CPack/OSXScriptLauncher.cxx)
Source/CMakeLists.txt:  target_link_libraries(OSXScriptLauncher cmsys)
Source/CMakeLists.txt:  target_link_libraries(OSXScriptLauncher "-framework CoreFoundation")
Source/CPack/cmCPackOSXX11Generator.cxx:      !this->CopyResourcePlistFile("OSXScriptLauncher.rsrc", dir, rsrcFile,
Source/CPack/cmCPackOSXX11Generator.cxx:      !this->CopyResourcePlistFile("OSXScriptLauncher", appdir,

$ git ls-files | grep OSXScriptLauncher
Modules/Internal/CPack/CPack.OSXScriptLauncher.in
Modules/Internal/CPack/CPack.OSXScriptLauncher.rsrc.in
Source/CPack/OSXScriptLauncher.cxx

$ file Modules/Internal/CPack/CPack.OSXScriptLauncher.in
Modules/Internal/CPack/CPack.OSXScriptLauncher.in: Mach-O universal binary with 2 architectures: [ppc:Mach-O ppc executable, flags:<NOUNDEFS|DYLDLINK|TWOLEVEL>] [i386:Mach-O i386 executable, flags:<NOUNDEFS|DYLDLINK|TWOLEVEL>]                                                         

It is likely that no one has been using this since it does not support the x86_64 architecture used by all modern macOS machines.