Add a addColumns method to PhutilConsoleTable.

Summary: Allow columns to be added in one big hit. In some cases, this may be easier than adding columns individually.

Test Plan: Meh

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9553