## Description 

Pretty simple -- allows serialization and deserialization of Move source
maps into a json format. This is to make it more amenable to being
utilized by tools written in languages that don't have access to BCS
(e.g., for use alongside tracing).

### PR Stack:
1. #18727 **<<<<< You are here**
2. #18729 
3. #18730 

## Test plan 

CI

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## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

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