Publish dhall-eta-all.jar in maven central

[jneira]

• Mentioned in twitter by @talios
• It would make dramatically easier to use in existing java/jvm projects
• It has the downside that it includes classes from eta, its core libraries, other haskell libraries and the apache bouncycastle library and use it with other eta projects or versions of bouncycastle could drive to incompabilities between different version of those classes.
  • So we should make clear that it should be used in isolation with other eta projects
• Afaiu maven central requires demonstrate the owner of the url that represents the group id (so if we want to use as group id org.dhall-lang f.e., we'll need the intervention of the https://dhall-lang.org owners)