Data source V2 API refactoring

Currently it's not very clear how we should abstract data source v2 API. The abstraction should be unified between batch and streaming, or similar but have a well-defined difference between batch and streaming. And the abstraction should also include catalog/table.

An example of the abstraction:

batch: catalog -> table -> scan
streaming: catalog -> table -> stream -> scan

We should refactor the data source v2 API according to the abstraction