make a wrapper for setup-environment

This is because repo does not allow symlinking and only copying
when we create sandbox. So we create a wrapper which will call
the real worker script which can change and when it changes we
do care for regenerating the environment

Change-Id: Ieda32b9c1072685fa0ad50e13393773cd63dde31
Signed-off-by: Khem Raj <raj.khem@gmail.com>