* initial work on improving snapshot performance

* Work on snapshots

* rename a few functions

* Cleanup the snapshot file

* vendor the safeio library

* Add a test

* Add more tests

* Some review comments

* Fix comment

* Update physical/raft/snapshot.go
Co-authored-by: Alexander Bezobchuk <alexanderbez@users.noreply.github.com>

* Update physical/raft/snapshot.go
Co-authored-by: Alexander Bezobchuk <alexanderbez@users.noreply.github.com>

* Review feedback
Co-authored-by: Alexander Bezobchuk <alexanderbez@users.noreply.github.com>