Specific OSGi loader for OsgiTestHolder. It's main usage is to load the
holder using a class-loader outside the OSGi world and to store results
there.
Boot delegation should work here but each platform has its own approach.
Notably, Equinox uses by default the boot (not the app) classloader which
means the classpath used for starting OSGi is not seen. To not interfere with
the default configuration which might change in the future (it has been
changed between 3.2 and 3.3) and to not impose restrictions on the test
usage, the loader manually discovers the proper classloader and uses it to
load the holder class. Inside OSGi, special care must be taken to make sure
no CCE are generated.