Reduce the verbosity of the `./bin/search index` script.

Summary: Currently, the `./bin/search index` script produces a lot of output (one line for every indexed object). Instead, use a `PhutilConsoleProgressBar` to indicate progress. This is much less verbose and gives a real indication of how long the script should take to complete.

Test Plan: Ran `./bin/search index` and verified that a progress bar was output.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9364