These classes do not depend on any Gerrit server functionality, and
could even be used to define an index without depending on the
gerrit-server package. This allows for a clearer separation of BUILD
rules; the QueryParser and antlr targets don't escape the gerrit-index
package.
The general layout thus far is to put index definition code in
com.google.gerrit.index, and query-related code (predicates, etc.) in
com.google.gerrit.index.query.
The gerrit-index package is still of limited utility on its own, because
QueryProcessor and InternalQuery still live in the server package, and
untangling their dependencies will still be a bit more work.
Change-Id: I3c4616d08ecf19d5ccd1b9b91b3fd0b1fcedd901
e47be68709