This PR:
* Added the clippy.toml to configure allowable expect / unwrap usage in
tests
* Removed as many expect/allow lines as possible from tests
* moved a bunch of allows to expects where possible
Note: in integration tests, non `#[test]` helper functions are not
covered by this so we had to leave a few lingering `expect(expect_used`
checks around
Previous to this PR, `codex-rs/core/tests/sandbox.rs` contained
integration tests that were specific to Seatbelt. This PR moves those
tests to `codex-rs/core/src/seatbelt.rs` and designates
`codex-rs/core/tests/sandbox.rs` to be used as the home for
cross-platform (well, Mac and Linux...) sandbox tests.
To start, this migrates
`python_multiprocessing_lock_works_under_seatbelt()` from #1823 to the
new `sandbox.rs` because this is the type of thing that should work on
both Mac _and_ Linux, though I still need to do some work to clean up
the test so it works on both platforms.
