There was no reason to have several different modules all providing a single
thing. This approach, which creates a single UtilsModule for everything in the
util package, is cleaner. This also removes provisioning of Random and
StringGenerator objects in RegistryConfig.ConfigModule, which don't belong
there because they aren't configuration options.
This also removes insecure random entirely; it was only used in a
single place to generate 24 bytes a couple times per day. We can live with the
lower speed if it means we don't have to worry about multiple types of Random,
or possibly using an insecure random accidentally in a place that security
actually does matter.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=229751915
