Normalize maximum time in MS parameter name, maxTimeMS vs max_time_ms

Currently, some operations such as aggregate() or count\_documents use maxTimeMS as parameter name, but others such as the find(), use max\_time\_ms, so unless you memorize which method uses which nomenclature, you have to check the docs every time. This is specially confusing since, for example, find\_one() uses max\_time\_ms but all the find\_one\_and\_...() methods use maxTimeMS.