Moved common macros to CustomTarget_Lo_Xcconfig.mk
to simplify each real target

added link to workdir/ios (needed by xcodeproj)

moved creation of configuration files to LO_Xcconfig, since
they are identical for all ios projects

central part of moving non git files to workdir completed

changed relative path in project.pbxproj to be <project> instead of <group>

Change-Id: I6be51f4d8a07ea7da08c0e5f1458fccfc3831a1e
Reviewed-on: https://gerrit.libreoffice.org/34223Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: jan iversen <jani@libreoffice.org>