Summary:
Added WAL and Snapshot explorer utility executables that read a wal or a
snapshot file and print the content of it, but the main purpose is that they
check it.
This is useful when debugging durability and want to know where it gets stuck.
Reviewers: dgleich, buda
Reviewed By: buda
Subscribers: ipaljak, vkasljevic, teon.banek, pullbot
Differential Revision: https://phabricator.memgraph.io/D1422
