Tracking Issue for RPC handlers
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### 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 a tracking issue for Cuprate's initial RPC handler implementation. The RPC handlers build upon the previous crates created in https://github.com/Cuprate/cuprate/issues/183. They implement the function bodies responsible for mapping requests to responses.

### Steps
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Describe the steps required to bring this effort to completion.

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- Internal changes required for RPC handlers
    - [x] https://github.com/Cuprate/cuprate/pull/266
    - [x] https://github.com/Cuprate/cuprate/pull/297
    - [x] https://github.com/Cuprate/cuprate/pull/300
    - [x] https://github.com/Cuprate/cuprate/pull/301
    - [x] https://github.com/Cuprate/cuprate/pull/309
    - [x] https://github.com/Cuprate/cuprate/pull/310
    - [x] https://github.com/Cuprate/cuprate/pull/320
- Handlers
    - [x] Initial skeleton, `fn` signatures, mappings
        - [x] https://github.com/Cuprate/cuprate/pull/262 
        - [x] https://github.com/Cuprate/cuprate/pull/272
    - [ ] Implementation: https://github.com/Cuprate/cuprate/pull/355
- Documentation
    - [ ] Architecture book: https://github.com/Cuprate/cuprate/pull/341

### Related
- https://github.com/Cuprate/cuprate/issues/183
- https://github.com/Cuprate/cuprate/issues/278
- https://github.com/Cuprate/cuprate/issues/279
- https://github.com/Cuprate/cuprate/pull/345

### TODO
- https://github.com/Cuprate/cuprate/pull/147#discussion_r1654885288
- https://github.com/Cuprate/cuprate/pull/147#discussion_r1654912900
- https://github.com/Cuprate/cuprate/pull/243#discussion_r1706267704