Add some generics flexibility to RootCodecRegistry
Added new helper API for admin functions

Removed old Administration classes, merged functionality into MongoDatabase / MongoCollection
Updated admin operations to follow builder style options.
Removed dropDups support
Minimal update of async / rx projects to updated operations
Added OperationExecutor to Mongo and now used in DB and DBCollection

JAVA-1332 JAVA-1412
Support legacy dropDups

JAVA-1412