refactor(v2): init events (#7823)

creates events structures for initial projections and read models

internal/v2/eventstore/postgres/intent.go

@@ -12,6 +12,11 @@ type intent struct {
 	sequence uint32
 }
 
+func (i *intent) nextSequence() uint32 {
+	i.sequence++
+	return i.sequence
+}
+
 func makeIntents(pushIntent *eventstore.PushIntent) []*intent {
 	res := make([]*intent, len(pushIntent.Aggregates()))