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/current_sequence.go

@@ -0,0 +1,29 @@
+package eventstore
+
+type CurrentSequence func(current uint32) bool
+
+func CheckSequence(current uint32, check CurrentSequence) bool {
+	if check == nil {
+		return true
+	}
+	return check(current)
+}
+
+// SequenceIgnore doesn't check the current sequence
+func SequenceIgnore() CurrentSequence {
+	return nil
+}
+
+// SequenceMatches exactly the provided sequence
+func SequenceMatches(sequence uint32) CurrentSequence {
+	return func(current uint32) bool {
+		return current == sequence
+	}
+}
+
+// SequenceAtLeast matches the given sequence <= the current sequence
+func SequenceAtLeast(sequence uint32) CurrentSequence {
+	return func(current uint32) bool {
+		return current >= sequence
+	}
+}