feat: actions v2 execution targets command side (#7384)

Adds the API to create, update, delete targets for execution in a new ExecutionService (v3alpha)

internal/repository/target/aggregate.go

@@ -0,0 +1,18 @@
+package target
+
+import "github.com/zitadel/zitadel/internal/eventstore"
+
+const (
+	AggregateType    = "target"
+	AggregateVersion = "v1"
+)
+
+func NewAggregate(aggrID, instanceID string) *eventstore.Aggregate {
+	return &eventstore.Aggregate{
+		ID:            aggrID,
+		Type:          AggregateType,
+		ResourceOwner: instanceID,
+		InstanceID:    instanceID,
+		Version:       AggregateVersion,
+	}
+}