feat(exceptions): support external client exception mappers

[shrirajpawar4]

🗒️ Description

Implements YAML-backed external exception mappers for client-owned error-string mappings.

Today, client exception mappings live in EEST Python source, so client teams need an execution-specs PR whenever their error strings change. This adds a small external mapper layer so client repos can
keep those mappings next to their client code while EEST keeps the built-in mappers as defaults.

External mappings are additive only:

• built-in Python mappers remain unchanged
• external YAML mappings extend the built-in mapper
• duplicate mapped exceptions are de-duplicated
• unknown messages still fall back to UndefinedException

YAML v1 format:

version: 1
name: geth-ci
substring:
  TransactionException.INSUFFICIENT_ACCOUNT_FUNDS:
    - "insufficient funds for gas * price + value"
regex:
  BlockException.INVALID_GASLIMIT:
    - 'child gas_limit \d+ .*'

Integration points:

- validate.toml:

  [geth]
  bin = "../go-ethereum/build/bin/evm"
  exception-mapper = "../go-ethereum/eest-exceptions.yaml"
- Hive consume:

  uv run consume engine --exception-mapper geth=../go-ethereum/eest-exceptions.yaml

This is stacked on #2622 because that PR introduces the new direct validate workflow where client-owned exception mappings are most useful for CI.

🔗 Related Issues or PRs

Fixes #2631.
Depends on #2622.

✅ Checklist

• All: Ran fast static checks to avoid unnecessary CI fails:

  just static

• All: PR title adheres to the repo standard and starts type(scope):.

• All: Considered updating the online docs in the ./docs/ directory.

• All: Set appropriate labels for the changes (only maintainers can apply labels).

Focused checks run:

uv run ruff check packages/testing/src/execution_testing/exceptions/external.py packages/testing/src/execution_testing/exceptions/__init__.py packages/testing/src/execution_testing/exceptions/tests/
test_external.py packages/testing/src/execution_testing/cli/pytest_commands/plugins/consume/simulators/exceptions.py packages/testing/src/execution_testing/cli/pytest_commands/plugins/consume/
simulators/sync/conftest.py packages/testing/src/execution_testing/cli/pytest_commands/plugins/consume/tests/test_exception_mappers.py packages/testing/src/execution_testing/cli/pytest_commands/
plugins/validate/conftest.py packages/testing/src/execution_testing/cli/pytest_commands/plugins/validate/tests/test_exception_mappers.py

uv run pytest packages/testing/src/execution_testing/exceptions/tests packages/testing/src/execution_testing/cli/pytest_commands/plugins/consume/tests packages/testing/src/execution_testing/cli/
pytest_commands/plugins/validate/tests/test_exception_mappers.py

Result: 41 passed, 5 warnings. The warnings are existing collect-only dummy consumer warnings.

[felix314159]

this pr is impossible to review right now. you should wait until the pr it depends on is merged and then rebase.

[shrirajpawar4]

yes okay