Add a ./bin/storage shell command
Summary: Fixes T7078. Adds a ./bin/storage shell command which passes through to a MySQL shell. This is slightly more convenient than running mysql manually.
Test Plan: Ran ./bin/storage shell and got a MySQL shell.
Reviewers: epriestley, Blessed Reviewers
Reviewed By: epriestley, Blessed Reviewers
Subscribers: Korvin, epriestley
Maniphest Tasks: T7078
Differential Revision: https://secure.phabricator.com/D11548