Extend shell helpers to allow setting 'comment' field to all commands.

After SERVER-29794 is implemented, all the commands will be able to attach 'comment' fields to the command object. Most of the shell helpers currently have an 'options' parameter using which any new field can be attached. But some helpers like 'explain' or 'insert' do not have this option. We need to audit all the major shell helper and allow options/comment parameter where necessary.