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/constraints.go

@@ -0,0 +1,25 @@
+package target
+
+import (
+	"github.com/zitadel/zitadel/internal/eventstore"
+)
+
+const (
+	UniqueTarget    = "target"
+	DuplicateTarget = "Errors.Target.AlreadyExists"
+)
+
+func NewAddUniqueConstraint(name string) *eventstore.UniqueConstraint {
+	return eventstore.NewAddEventUniqueConstraint(
+		UniqueTarget,
+		name,
+		DuplicateTarget,
+	)
+}
+
+func NewRemoveUniqueConstraint(name string) *eventstore.UniqueConstraint {
+	return eventstore.NewRemoveUniqueConstraint(
+		UniqueTarget,
+		name,
+	)
+}