The base class for ServiceEntryPoint is mixing two separate services:

• SessionManager that should be responsible for accepting new connections/streams and providing them with their own instance of SessionWorkflow. All the virtual interfaces defined by the base class concern managing sessions, except for two: handleRequest and slowSessionWorkflowLogSeverity.
• ServiceEntryPoint that should provide the interface for accessing the database (e.g., through ServiceEntryPointCommon::handleRequest).

We should reorganize this hierarchy by:

• Splitting SessionManager into its own class, and having ServiceContext own a single instance of SessionManager. Initially, we'll only need two implementations of SessionManager since mongod and mongos have slightly different implementations for this class today. We also need to implement an extension for Mongo embedded similar to how it's implemented today.
• Merging ServiceEntryPointCommon with ServiceEntryPoint, and making ServiceEntryPointMongod, ServiceEntryPointEmbedded, and ServiceEntryPointMongos have that as their base class.

There are also three tests that must be adjusted as part of this modification/refactoring.