Prepare for InnoDB FULLTEXT support

Summary:
Ref T11741. This makes everything work if we switch to InnoDB, but never actually switches yet.

Since the default minimum word length (3) and stopword list (36 common English words) in InnoDB are generally pretty reasonable, I just didn't add any setup advice for them. I figure we're better off with simpler setup until we identify some real problem that the builtin stopwords create.

Test Plan: Swapped the false to true, ran storage adjust, got InnoDB fulltext indexes, searched for stuff, got default "AND" behavior.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11741

Differential Revision: https://secure.phabricator.com/D16942