Add "bin/search query" for debugging query execution

Summary:
Ref T13000. Currently, queries can only be executed from the web UI, which requires logging in as a user. I really want to avoid doing that wherever we can, but being able to execute queries on an instance (and, particularly, see the ngrams and timings on the underlying lookups) would have been helpful in several cases.

Improve tooling a bit in advance of the "common ngrams" stuff going out since it seems likely that it will be useful if issues arise.

Test Plan: Ran bin/search query --query ..., got useful minimal output. Ran with --trace to get internals.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13000

Differential Revision: https://secure.phabricator.com/D18690