Tracking Issue for RPC integration
### About tracking issues
Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter.

### What
This is the 3rd tracking issue surrounding the initial RPC implementation in `cuprated`.

The scope is:
- Practical input/output compatibility with `monerod`
- Compatibility with existing wallets
- Request/response call stack for each method
- Integration into `cuprated` i.e. RPC server on `18081/18089` 
- End-user RPC documentation

### Steps

- Internal request/response call stack
    - [ ] TODO 
- [ ] `cuprated` <-> `monerod` RPC input/output testing harness: https://github.com/Cuprate/cuprate/pull/357
- Method enabling
    - Required for wallet compatibility
        - [ ] TODO
    - Useful but optional
        - [ ] TODO    
    - Everything else
        - [ ] TODO
- [ ] Public RPC server
- [ ] Private RPC server
- Documentation
    - [ ] User Book
    - [ ] Architecture Book

### Related

- https://github.com/Cuprate/cuprate/issues/183
- https://github.com/Cuprate/cuprate/issues/244