Provide some "preg_*" wrappers which raise exceptions on failure

Summary: Ref T13608. Ref T13100. Ref T13586. Properly checking "preg_match()" and similar calls for failure and raising useful exceptions is complicated and error-prone. Provide wrapper functions with an API that's more consistent with the rest of the codebase: matches are returned; and errors raise detailed exceptions.

Test Plan: See next change.

Maniphest Tasks: T13608, T13586, T13100

Differential Revision: https://secure.phabricator.com/D21561