Changes 'next_errors' variable in main decoding loop to a linked list

[dandragona-dev]

• Prevents unnecessary vector copies as we can just rebuild the history when we need to.
• Also use arena allocator to prevent repeated heap allocation.

Tested with:

(venv13) dandragona@kaonashi:~/Documents/tesseract/indep/optimizations$ bazel-8.2.1 test --cache_test_results=no //src:all //src/py:all
INFO: Analyzed 24 targets (0 packages loaded, 23 targets configured).
INFO: Found 16 targets and 8 test targets...
INFO: Elapsed time: 6.390s, Critical Path: 5.97s
INFO: 9 processes: 42 action cache hit, 12 linux-sandbox, 2 local.
INFO: Build completed successfully, 9 total actions
//src:common_tests                                                       PASSED in 0.0s
//src:tesseract_tests                                                    PASSED in 0.7s
//src/py:common_test                                                     PASSED in 1.5s
//src/py:requirements_test                                               PASSED in 5.9s
//src/py:simplex_test                                                    PASSED in 1.6s
//src/py:tesseract_sinter_compat_test                                    PASSED in 4.6s
//src/py:tesseract_test                                                  PASSED in 1.5s
//src/py:utils_test                                                      PASSED in 1.0s

Executed 8 out of 8 tests: 8 tests pass.

Additional accuracy comparisons:

# d=11, p=0.001 Surface Code Transversal CNOT X
# baseline:
num_shots = 5000 num_low_confidence = 0 num_errors = 25 total_time_seconds = 364.1171770000001
# arena allocator + linked list optimization:
num_shots = 5000 num_low_confidence = 0 num_errors = 25 total_time_seconds = 253.3283590000004


# d=9, p=.002 Superdense Color Code X
# baseline:
num_shots = 5000 num_low_confidence = 0 num_errors = 64 total_time_seconds = 604.9724190000003
# arena allocator + linked list optimization:
num_shots = 5000 num_low_confidence = 0 num_errors = 64 total_time_seconds = 585.220854999997


# d=12, p=0.002 Bivariate Bicycle X
# baseline:
num_shots = 5000 num_low_confidence = 0 num_errors = 15 total_time_seconds = 3232.868145999989
# arena allocator + linked list optimization:
num_shots = 5000 num_low_confidence = 0 num_errors = 15 total_time_seconds = 3099.478287000002


# d=23, p=0.008 Surface Code Unrotated Memory Z
# baseline:
num_shots = 5000 num_low_confidence = 0 num_errors = 0 total_time_seconds = 803.0619609999993
# arena allocator + linked list optimization:
num_shots = 5000 num_low_confidence = 0 num_errors = 0 total_time_seconds = 142.359363