Scala SDK

[patriknw]

Task breakdown:

• Build project structure in this repo #382
• Public API in Scala, corresponding to .java in com.akkaserverless.javasdk, share same impl as Java SDK #381
• sbt plugin for codegen sbt plugin for Scala codegen #379
• Codegen of Scala, corresponding to codegenJava
• .g8 template, corresponding to the maven archetype
• Samples and documentation, use Java/Scala tabs
• TCK tests Scala TCK implementation #564
• Update the README.md
• Demo https://github.com/lightbend/akkaserverless-docs/issues/1022

Subtasks for public api and codgen:

• Main and AkkaServerlessFactory (@patriknw)
• ValueEntity
• EventSourcedEntity feat(scalasdk): EventSourcedEntity Public API. #538
• Codegen for EventSourcedEntity, corresponding to codegenJava #560
• Actions (@octonato) feat(scalasdk): Actions API #433, feat(scalasdk): generate action sources for Scala SDK #447
• Views (@patriknw)
• TestKit for ValueEntity (@patriknw)
• TestKit for EventSourcedEntity Eventsourced entity testkit #584
• TestKit for ValueEntity and EventSourcedEntity: support for testing 'forward' Support for testing 'forward' #587
• Integration tests for ValueEntity feat(scala-sdk): Integration test template #565
• Integration tests for EventSourcedEntity feat(codegen-scala): add EventSourcedEntity IntegrationSpec template #592
• ReplicatedEntity (@octonato) feat(scalasdk): replicated entity for Scala API #541