Provide a mapping from OperationKey to CursorID

We introduced OperationKeys as part of SERVER-44167, which allows a user to provide a GUID in any command which it can later be killed by via the killOperations command.

We'd like to extend that functionality to also kill cursors created by that OperationKey, and would like to see if we can tag those UUIDs onto cursors and provide an accessor which gives a list of cursor ids for a given list operation keys (because we bulk kill operations).

Ideally I'd want something like:

std::vector<CursorId> getCursorIdsForOperationKeys(std::vector<OperationKey>)

as a method on the cursor manager. That way I could write an external service to lookup those ids and kill them through the public api.

Optionally, I'd also be happy to consider a killCursor method which took a vector of OperationKeys