develop
Integration of all external packages into MassTransit, split out into Abstractions, Middleware, and the core MassTransit assembly.
Simple optimization from an old branch, copied over.
Standardized the topology for partition key across service bus, event hub, and the SQL transport
Refactored RoutingKey send topology formatter into the main assembly (used by gRPC and RabbitMQ, also the Database Transport)
Fixed #4240 - Added ability to specify message type specific serialization content type
Fixed #4697 - CorrelationId property from base classes and interfaces will be used if present.