Implement a new member function in the Collection API called latestSizeCount() that returns the fully accurate collection size/count, even after shutdown. We expect ReplicatedFastCountManager::findLatest() to incur significant overhead to size/count lookups, so only use the function where required:
1. User commands (count, dataSize)

2. Validation

3. Capped collections

Future work in SERVER-121777 will replace the numRecords() and dataSize() implementations with persistedSizeCount() which will only contains changes to the collection's size/count as of the last checkpoint. This will be much more performant because there is no oplog traversal involved.