Port the Java fragment lexer to PHP

Summary:
Ref T13195. Ref T3130. Ports the lexer for Java code from Python to PHP.

This isn't 100% faithful to the behavior in Pygments, but pretty close. We can improve it as the need arises.

Test Plan:

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13195, T3130

Differential Revision: https://secure.phabricator.com/D19637