Add Support for startAfter in Reactive MongoDB Change Streams

[luketn]

Description

The ChangeStreamOptions support in Quarkus Reactive Mongo Client allows you to specify most parameters to the underlying ChangeStreamPublisher from the Reactive Mongo Client.

One missing option however is the startAfter(resumeToken) method.

This is an important method, because if the collection you are watching is dropped the resume token can only be used with startAfter, not resumeAfter.
Ref: https://www.mongodb.com/docs/manual/changeStreams/#startafter-for-change-streams

Implementation ideas

Pull request to follow with implementation.

[quarkus-bot]

/cc @evanchooly, @loicmathieu