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.go

@@ -0,0 +1,36 @@
+package eventstore
+
+import "time"
+
+type Event[P any] struct {
+	Aggregate Aggregate
+	CreatedAt time.Time
+	Creator   string
+	Position  GlobalPosition
+	Revision  uint16
+	Sequence  uint32
+	Type      string
+	Payload   P
+}
+
+type StoragePayload interface {
+	Unmarshal(ptr any) error
+}
+
+func EventFromStorage[E Event[P], P any](event *Event[StoragePayload]) (*E, error) {
+	var payload P
+
+	if err := event.Payload.Unmarshal(&payload); err != nil {
+		return nil, err
+	}
+	return &E{
+		Aggregate: event.Aggregate,
+		CreatedAt: event.CreatedAt,
+		Creator:   event.Creator,
+		Position:  event.Position,
+		Revision:  event.Revision,
+		Sequence:  event.Sequence,
+		Type:      event.Type,
+		Payload:   payload,
+	}, nil
+}