Shell helper to get a single collection's options document

For writing jstests or general deployment debugging, it would be useful to have easy access to collection metadata. Previously, this data was available by querying the system.namespaces collection, but that is no longer supported with new storage engines. It would be very helpful to have a shell helper to wrap the listCollections command and return just the collection object for a single collection.

This could be implemented as a db method, i.e.

db.collectionOptions("myCollection")

or added to the collection prototype

db.myCollection.options()