feat(outbox): verify outbox proofs

[victor-dumitrescu]

Closes RV-879.

What

The outbox can now verify an outbox proof.

Why

The outbox needs to support verifying inclusion proofs for messages.

How

Outbox proof verification employs the same mechanism used for fraud proofs. The difference is that the verified state transition is not one step of the PVM but a successful read of the given message from the outbox.

Manually Testing

make all

In particular, the test_outbox_proofs_dummy_kernel test.

Regressions

Tasks for the Author

• Link all Linear issues related to this MR using magic words (e.g. part of, relates to, closes).
• Eliminate dead code and other spurious artefacts introduced in your changes.
• Document new public functions, methods and types.
• Make sure the documentation for updated functions, methods, and types is correct.
• Add tests for bugs that have been fixed.
• Explain changes to regression test captures when applicable.
• Write commit messages in agreement with our guidelines.
• Self-review your changes to ensure they are high-quality.
• Complete all of the above before assigning this MR to reviewers.

[codecov]

Codecov Report

❌ Patch coverage is 88.23529% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.16%. Comparing base (301d866) to head (3a51206).

Files with missing lines	Patch %	Lines
src/riscv/lib/src/pvm/node_pvm.rs	0.00%	3 Missing ⚠️
src/riscv/lib/src/stepper/pvm.rs	96.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           vdum/rv-877     #809      +/-   ##
===============================================
- Coverage        91.16%   91.16%   -0.01%     
===============================================
  Files              110      110              
  Lines            21206    21235      +29     
  Branches         21206    21235      +29     
===============================================
+ Hits             19333    19359      +26     
- Misses            1498     1501       +3     
  Partials           375      375              

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