Add Oracle tests for MIPS

[martyall]

This PR consists of two commits

• d98442c: Add cannon mips tests for oracle reads/writes:
  -- oracle.asm
  -- oracle_kzg.asm
  -- oracle_unaligned_read.asm
  -- oracle_unaligned_write.asm
• c5095ad: Make modifications to SyscallWritePreimage handler to get tests to pass

The test was adapted from the cannon codebase version. None of these oracle based tests passed with the current implementation. The problem was with the SyscallWritePreimage syscall handler, which if you look at the test logs for d98442c you can see the errors of the form:

[2025-01-13T16:18:51Z DEBUG o1vm::elf_loader] The executable code starts at address 4194512, has size 304 bytes, and ends at address 4194815.
[2025-01-13T16:18:51Z DEBUG test_mips_elf::test_oracle] Asking oracle for key: 000000000000000000000000000000000000000000000000000000004a29921f
thread 'tests::open_mips_tests' panicked at 'Unknown key type prefix: 0', o1vm/tests/test_mips_elf.rs:62:22

If you want to run them locally, you can use the one-liner

> RUST_LOG=debug RUST_BACKTRACE=1 cargo test --features open_mips --test test_mips_elf -- --nocapture

The problem is that the current write handler isn't writing to the appropriate places in the register. I came up with a solution that fixes the problem with the cost of increasing the scratch space and the number of registers. If we're looking to "pay less" for the correct implementation, we can use this as a starting point.

[codecov]

Codecov Report

Attention: Patch coverage is 97.59036% with 2 lines in your changes missing coverage. Please review.

Project coverage is 76.59%. Comparing base (2136d6c) to head (c5095ad).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
o1vm/src/cannon.rs	0.00%	1 Missing ⚠️
o1vm/src/interpreters/mips/registers.rs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2945      +/-   ##
==========================================
- Coverage   76.61%   76.59%   -0.02%     
==========================================
  Files         255      255              
  Lines       60855    60791      -64     
==========================================
- Hits        46622    46564      -58     
+ Misses      14233    14227       -6     

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