This solves two problems:

• Upcoming changes to support a new TicketHolder subclass based on Notifyable waiter lists requires access to the Waitable it waits upon (in practice this is always a Baton instance). Giving TicketHolder api access to the opCtx in turn gives the implementation access to the Baton associated with that opCtx.
• The TicketHolder resize API currently is uninterruptible. Passing in an opCtx to those methods allows us to check for interrupt.