Add builtin CLI profiling to every PhutilArgumentParser script

Summary: Add support for an "--xprofile" arg as part of the standard arg bundle.

Test Plan:
Ran utf8.php --xprofile derp.xhprof; then arc upload derp.xhprof and then viewed the profile via the web UI.

(Those last two steps could be a little easier.)

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1826