Add 'SequentialGuid' IDistinctGenerator<Guid> implementation

[carusology]

Sequential GUIDs increase the statistical likelihood of conflicts when creating random GUIDs to be used in large quantities, as you use a deterministic approach to generate the leading bytes of a GUID. However, they also provide optimal throughput when inserting them into databases, as they will get inserted into an indexed column on a database as the same logical block/page of space will get used.

Since there are times we will want to take this improved throughput over improved distribution of randomness, we should make a "SequentialGuid" generator implementation that we can use in our projects.