[BitSail][Feature] Support a simple source split coordinator.

[BlockLiu]

Is your feature request related to a problem? Please describe

BitSail use SourceSplitCoordinator to assign splits to reader connectors.

In batch scenarios, the SourceSplitCoordinator usually computes all splits at first, and then make a assignment plan.

We want to implement an abstract SourceSplitCoordinator class to support such batch scenarios.

Describe the solution you'd like

Support a simple abstract SourceSplitCoordinator class.

[john8628]

i will try it, please assign to me

[BlockLiu]

Hi @john8628, do you have any progress or question on this issue? Please let us know if you meet any problem.