refactor(v2): init eventstore package (#7806)

* refactor(v2): init database package

* refactor(v2): init eventstore package

* add mock package

* test query constructors

* option based push analog to query

internal/v2/eventstore/event_store.go

@@ -0,0 +1,41 @@
+package eventstore
+
+import (
+	"context"
+)
+
+func NewEventstore(querier Querier, pusher Pusher) *EventStore {
+	return &EventStore{
+		Pusher:  pusher,
+		Querier: querier,
+	}
+}
+
+func NewEventstoreFromOne(o one) *EventStore {
+	return NewEventstore(o, o)
+}
+
+type EventStore struct {
+	Pusher
+	Querier
+}
+
+type one interface {
+	Pusher
+	Querier
+}
+
+type healthier interface {
+	Health(ctx context.Context) error
+}
+
+type GlobalPosition struct {
+	Position        float64
+	InPositionOrder uint32
+}
+
+type Reducer interface {
+	Reduce(events ...*Event[StoragePayload]) error
+}
+
+type Reduce func(events ...*Event[StoragePayload]) error