feat(eventstore): increase parallel write capabilities (#5940)

This implementation increases parallel write capabilities of the eventstore.
Please have a look at the technical advisories: [05](https://zitadel.com/docs/support/advisory/a10005) and  [06](https://zitadel.com/docs/support/advisory/a10006).
The implementation of eventstore.push is rewritten and stored events are migrated to a new table `eventstore.events2`.
If you are using cockroach: make sure that the database user of ZITADEL has `VIEWACTIVITY` grant. This is used to query events.

internal/eventstore/v3/mock_test.go

@@ -0,0 +1,64 @@
+package eventstore
+
+import (
+	"github.com/zitadel/zitadel/internal/eventstore"
+)
+
+var _ eventstore.Command = (*mockCommand)(nil)
+
+type mockCommand struct {
+	aggregate   *eventstore.Aggregate
+	payload     any
+	constraints []*eventstore.UniqueConstraint
+}
+
+// Aggregate implements [eventstore.Command]
+func (m *mockCommand) Aggregate() *eventstore.Aggregate {
+	return m.aggregate
+}
+
+// Creator implements [eventstore.Command]
+func (m *mockCommand) Creator() string {
+	return "creator"
+}
+
+// Revision implements [eventstore.Command]
+func (m *mockCommand) Revision() uint16 {
+	return 1
+}
+
+// Type implements [eventstore.Command]
+func (m *mockCommand) Type() eventstore.EventType {
+	return "event.type"
+}
+
+// Payload implements [eventstore.Command]
+func (m *mockCommand) Payload() any {
+	return m.payload
+}
+
+// UniqueConstraints implements [eventstore.Command]
+func (m *mockCommand) UniqueConstraints() []*eventstore.UniqueConstraint {
+	return m.constraints
+}
+
+func mockEvent(aggregate *eventstore.Aggregate, sequence uint64, payload Payload) eventstore.Event {
+	return &event{
+		aggregate: aggregate,
+		creator:   "creator",
+		revision:  1,
+		typ:       "event.type",
+		sequence:  sequence,
+		payload:   payload,
+	}
+}
+
+func mockAggregate(id string) *eventstore.Aggregate {
+	return &eventstore.Aggregate{
+		ID:            id,
+		Type:          "type",
+		ResourceOwner: "ro",
+		InstanceID:    "instance",
+		Version:       "v1",
+	}
+}