Similarly to the proxy port handling, we should check for conflicts between the maintenance port and the main/proxy ports and then pass this information into lower layers.

Currently, port conflict checks and feature flag checks for new ports are performed in mongod_main (and the GRPC checks are done both there and in mongos_main). Since we are adding a new usage which will also need to be checked in both places, we should move these checks into the transport layer manager file and consolidate the logic from mongoS and mongoD. Additionally, we should provide a port conflict checking logic which is easily extended for more port specifications in the future.