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/test/kotlin/eventDemo/libs/event/VersionBuilderLocalTest.kt

@@ -0,0 +1,42 @@
+package eventDemo.libs.event
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.equals.shouldBeEqual
+import kotlinx.coroutines.DelicateCoroutinesApi
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.joinAll
+import kotlinx.coroutines.launch
+
+@OptIn(DelicateCoroutinesApi::class)
+class VersionBuilderLocalTest :
+    FunSpec({
+
+        test("buildNextVersion") {
+            VersionBuilderLocal().run {
+                buildNextVersion() shouldBeEqual 1
+                buildNextVersion() shouldBeEqual 2
+                buildNextVersion() shouldBeEqual 3
+            }
+        }
+
+        test("buildNextVersion concurrently") {
+            val versionBuilder = VersionBuilderLocal()
+            (1..20)
+                .map {
+                    GlobalScope.launch {
+                        (1..1000).map {
+                            versionBuilder.buildNextVersion()
+                        }
+                    }
+                }.joinAll()
+            versionBuilder.getLastVersion() shouldBeEqual 20 * 1000
+        }
+
+        test("getLastVersion") {
+            VersionBuilderLocal().run {
+                getLastVersion() shouldBeEqual 0
+                getLastVersion() shouldBeEqual 0
+                getLastVersion() shouldBeEqual 0
+            }
+        }
+    })