[11u] [JVMCI] Partial module-info.java backport of JDK-8223332

JDK-8223332 updated JVMCI in jdk head (JDK 13 timeframe). That rather large patch includes some module-info.java updates for the jdk.internal.vm.ci module so as to export the 'code' package to the jdk.internal.vm.compiler module.

This module export is needed for using native-image (the binary over the launcher script) of Graal VM with OpenJDK 11.

See also: https://github.com/graalvm/mandrel/issues/234

Rather than backporting the large patch of JDK-8223332 to a stable updates release I propose to only backport the module-info.java changes so as to reduce risk.