If a create command requests for a v:1 _id index, using the idIndex parameter, we don't seem to be logging the _id index specification in the oplog. Since we are now exposing the create operation in the change stream events(which relies on oplog to fetch the command specification), it would be good we can log the index spec for v:1 index, as we do when it's v:2 index.

Additionally, we are also ignoring the idIndex.name parameter (for both v:1 and v:2) for create.command, which could be misleading for the users. We should either disallow users from specifying it, or store the user provided name.