Writing a Jigsaw-modular Kotlin program which doesn't require
kotlin.stdlib doesn't make sense because it most likely will fail at
runtime, on access to anything from the standard library. Previously, we
checked that kotlin.stdlib was in the module graph, but that's not
enough, we should also check that the source module requires it.
'-Xallow-kotlin-package' can be used to disable the error.
Add a test checking that an indirect (transitive) dependency is also OK
Also report the "named does not read unnamed" error, which was not
possible previously because we wouldn't be able to read anything from
kotlin-stdlib (because it was added to the unnamed module by default)
