Summary:
This diff introduces the IntervalSet data structure, which will be used to help create sets of non overlapping sets of intervals for MultiScan scan options. Specifically, we add specializations for Slices to assist in this.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/13787
Test Plan: Added test to catch various cases within adding intervals.
Reviewed By: anand1976
Differential Revision: D78624970
Pulled By: krhancoc
fbshipit-source-id: 9a3e4a28738ab8428788467540fc05ab5c1a1b67