RE2/J fork for Trino

This fork of Google RE2/J which is a port of Google RE2 to pure Java. The main difference is that this fork contains a port of the RE2 DFA, which is not part of RE2/J. Additionally, there are some performance improvements, and the code has been changed from Java String to Slice, which is a byte[] wrapper used by the Trino project.

Please see the Google projects for more information about RE2.