[Feature Request] OpLog support

[AlekSi]

Purpose of the feature.

https://www.mongodb.com/docs/manual/core/replica-set-oplog/

Having OpLog support in DocumentDB would enable the following:

• replication to and from MongoDB;
• Meteor OpLog tailing.

Describe the solution you'd like

OpLog is implemented in DocumentDB. OpLog collection is a capped collection, so this issue is blocked by #47.

Describe alternatives you've considered

Implement capped collections and OpLog in FerretDB. If change streams (#50) are implemented, that should be easy. Without them, that would be very hard.

Additional context

N/A