Once we have split the CurOp/OpDebug metrics into their own classes and files, we should revisit the modularization tags added in SERVER-111201.

Ideally, most of the CurOp/OpDebug public methods will be able to be made private to the query module (the classes themselves and some functions, e.g. CurOp::get(), will have to remain public so that they can be accessed everywhere). Each metrics class/file can be assigned to the right module and (hopefully) be made module-private.