Extract commitment-config crate

[kevinheavey]

Problem

solana_sdk::commitment_config imposes a solana_sdk dependency on solana_rpc_client

Summary of Changes

• move commitment_config.rs to its own crate
• make serde optional in the new crate
• re-export it in solana-sdk (with serde enabled)

[febo]

It seems that CommitmentConfig is always used in combination with RpcClient so I wonder whether they should be on the same crate or not. Not sure if there is a scenario where we would use CommitmentConfig and not the RpcClient.

[kevinheavey]

It seems that CommitmentConfig is always used in combination with RpcClient so I wonder whether they should be on the same crate or not. Not sure if there is a scenario where we would use CommitmentConfig and not the RpcClient.

It's also used in the Client and AsyncClient traits in solana_sdk::client, and in solana-banks-client

[febo]

It seems that CommitmentConfig is always used in combination with RpcClient so I wonder whether they should be on the same crate or not. Not sure if there is a scenario where we would use CommitmentConfig and not the RpcClient.

It's also used in the Client and AsyncClient traits in solana_sdk::client, and in solana-banks-client

Not sure why my search did not return those uses but I can see them there. 😅

[febo]

Looks good - just waiting for the crate + CI to pass before approving.

cc: @yihau

[yihau]

✅