Summary:
In Raft, we often need to access persistent state of the server
without modifying it. In order to speed up such operations, we
keep an in-memory copy of that state.
In this diff we make a copy of all persistent state except for
the log itself. Running our feature benchmark locally, we manage
to increase the throughput for cca 750 queries/s.
Reviewers: msantl
Reviewed By: msantl
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1843