extract projection snapshot logic

implement GameStateRepositoryTest
add lambda to the GameEventHandler.handle{} to set the version

add VersionBuilder
add version to the events
add creation date to the events
rename gameId to aggregateId
add EventHandler interface

src/main/kotlin/eventDemo/app/event/EventHandler.kt

@@ -0,0 +1,13 @@
+package eventDemo.app.event
+
+import eventDemo.libs.event.AggregateId
+import eventDemo.libs.event.Event
+
+/**
+ * A stream to publish and read the played card event.
+ */
+interface EventHandler<E : Event<ID>, ID : AggregateId> {
+    fun registerProjectionBuilder(builder: (E) -> Unit)
+
+    fun handle(buildEvent: (version: Int) -> E): E
+}