Default DA Clients

This crate contains the default implementations of the Data Availability clients. Default clients are maintained within this repo because they are tightly coupled with the codebase, and would cause the circular dependency if they were to be moved to the hyperchain-da repository.

Currently, the following DataAvailability clients are implemented:

• NoDA client that does not send or store any pubdata, it is needed to run the zkSync network in the "no-DA" mode utilizing the DA framework.
• Object Store client that stores the pubdata in the Object Store(GCS).