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/postgres/event.go

@@ -0,0 +1,64 @@
+package postgres
+
+import (
+	"encoding/json"
+
+	"github.com/zitadel/logging"
+
+	"github.com/zitadel/zitadel/internal/v2/eventstore"
+	"github.com/zitadel/zitadel/internal/zerrors"
+)
+
+func intentToCommands(intent *intent) (commands []*command, err error) {
+	commands = make([]*command, len(intent.Commands()))
+
+	for i, cmd := range intent.Commands() {
+		var payload unmarshalPayload
+		if cmd.Payload() != nil {
+			payload, err = json.Marshal(cmd.Payload())
+			if err != nil {
+				logging.WithError(err).Warn("marshal payload failed")
+				return nil, zerrors.ThrowInternal(err, "POSTG-MInPK", "Errors.Internal")
+			}
+		}
+
+		commands[i] = &command{
+			Event: &eventstore.Event[eventstore.StoragePayload]{
+				Aggregate: *intent.Aggregate(),
+				Creator:   cmd.Creator(),
+				Revision:  cmd.Revision(),
+				Type:      cmd.Type(),
+				// always add at least 1 to the currently stored sequence
+				Sequence: intent.sequence + uint32(i) + 1,
+				Payload:  payload,
+			},
+			intent:            intent,
+			uniqueConstraints: cmd.UniqueConstraints(),
+		}
+	}
+
+	return commands, nil
+}
+
+type command struct {
+	*eventstore.Event[eventstore.StoragePayload]
+
+	intent            *intent
+	uniqueConstraints []*eventstore.UniqueConstraint
+}
+
+var _ eventstore.StoragePayload = (unmarshalPayload)(nil)
+
+type unmarshalPayload []byte
+
+// Unmarshal implements eventstore.StoragePayload.
+func (p unmarshalPayload) Unmarshal(ptr any) error {
+	if len(p) == 0 {
+		return nil
+	}
+	if err := json.Unmarshal(p, ptr); err != nil {
+		return zerrors.ThrowInternal(err, "POSTG-u8qVo", "Errors.Internal")
+	}
+
+	return nil
+}