Change "%s" in qsprintf to exclude non-BMP characters

Summary:
Ref T1191. Make `%s` in qsprintf reject non-BMP characters. Introduce `%B` for escaping binary strings.

Basically, this just makes "yes, I want to put binary data in this column" explicit.

Test Plan: See next diff for test coverage in Phabricator.

Reviewers: btrahan, arice

Reviewed By: arice

CC: chad, arice, aran

Maniphest Tasks: T1191

Differential Revision: https://secure.phabricator.com/D8315