The sharding_catalog_manager is a library designed to manage the DDL flow, its infrastructure, the global catalog, and its maintenance. To achieve this, it should be built on top of sharding_runtime_d, which should serve as the library exposing the API to interact with the shard catalog.

Currently, this is not the case - sharding_runtime_d depends on sharding_catalog_manager. We should reverse this dependency as a clear first step toward modularization.