## Description 

When rpc_url is not specified, previously the sui-tool would iterate
through the network config and try each config one by one. This is
rather unnecessary and inefficient.
This PR adds an explicit --chain option so that when rpc_url is not
specified, it will use the config named `chain` in the config file. This
simplifies some of the implementation and makes it faster to replay a
transaction when the desired config is not the first one in the config
file.

## Test plan 

CI
Run locally

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## Release notes

Check each box that your changes affect. If none of the boxes relate to
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any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK: