chore: move the go code into a subfolder

apps/api/internal/eventstore/handler/v2/reduce.go

@@ -0,0 +1,21 @@
+package handler
+
+import "github.com/zitadel/zitadel/internal/eventstore"
+
+// EventReducer represents the required data
+// to work with events
+type EventReducer struct {
+	Event  eventstore.EventType
+	Reduce Reduce
+}
+
+// Reduce reduces the given event to a statement
+// which is used to update the projection
+type Reduce func(eventstore.Event) (*Statement, error)
+
+// EventReducer represents the required data
+// to work with aggregates
+type AggregateReducer struct {
+	Aggregate     eventstore.AggregateType
+	EventReducers []EventReducer
+}