Crdt Tree Node ID
data class CrdtTreeNodeID : Comparable<CrdtTreeNodeID> , JsonSerializable<CrdtTreeNodeID, CrdtTreeNodeIDStruct>
CrdtTreeNodeID represent an ID of a node in the tree. It is used to identify a node in the tree. It is composed of the creation time of the node and the offset from the beginning of the node if the node is split.
Some of replicas may have nodes that are not split yet. In this case, we can use map.floorEntry()
to find the adjacent node.