Add `bin/storage adjust`, for adjusting schemata

Summary:
Ref T1191. Adds a new workflow which can apply schema adjustments.

For now, it only performs database and table collation/charset adjustments. I believe these are extremely safe/minor, because they only affect the default values for newly created columns.

Test Plan:
  - Ran migration on various database states, database/table changes went through cleanly.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T1191

Differential Revision: https://secure.phabricator.com/D10595