[Kernel] [CC Refactor #2] Add `TableDescriptor` and `CommitCoordinatorClient` API

[scottsand-db]

This is a stacked PR. Please view this PR's diff here:

• https://github.com/scottsand-db/delta/compare/delta_kernel_cc_1...delta_kernel_cc_2

Which Delta project/connector is this regarding?

• [ ] Spark
• [ ] Standalone
• [ ] Flink
• [X] Kernel
• [ ] Other (fill in here)

Description

Adds new TableDescriptor and CommitCoordinatorClient API. Adds a new getCommitCoordinatorClient API to the Engine (with a default implementation that throws an exception).

How was this patch tested?

N/A trivial.

Does this PR introduce any user-facing changes?

Yes. See the above.