[GR-30433] Make native-image driver buildable via --module-path.

[olpaw]

The changes on this PR further refine native-image module support to a point where we can now build the native-image driver into and image if svm-driver.jar is specified on the --module-path. I.e. The following works now:

cd graal/substratevm
export USE_NATIVE_IMAGE_JAVA_PLATFORM_MODULE_SYSTEM=true
mx build
mx native-image -g -ea --module-path svmbuild/vm/lib/graalvm/svm-driver.jar --module org.graalvm.nativeimage.driver/com.oracle.svm.driver.NativeImage -H:Path=svmbuild/vm/lib/svm/bin -H:Name=native-image

and results in a working driver image. Which can easily tested with e.g.

svmbuild/vm/lib/svm/bin/native-image -g -ea --module-path svmbuild/vm/lib/graalvm/svm-driver.jar --module org.graalvm.nativeimage.driver/com.oracle.svm.driver.NativeImage -H:Path=svmbuild/vm/lib/svm/bin -H:Name=native-image

[olpaw]

Heads up: The remains of the previously to experimental demoted native-image build server mode will be removed soon.
With all the changes for module-support it is impossible to keep the server specific sources in a consistent state. See:

8130b75