GH-120754: Add a strace helper and test set of syscalls for open().read() by cmaloney · Pull Request #121143 · python/cpython

The test explicitly wants to check for `vfork` call _or_ flag passed to
clone so keep doing the regex search rather than looking at particular
events

Goal is that as changes to I/O code are made changes to the set of
system calls made need to be intentional so that common fast-paths
aren't accidentally changed.

NOTE: This needs a full buildbot test pass before merge, see: python#121143 (comment).

1. Added `statx` to set of allowed syscall forms (Should make Raspian bot pass).
2. Check that the `fd` returned from `open` is passed to all future calls. This helps ensure things like the `stat` call uses the file descriptor rather than the `filename` to avoid TOCTOU isuses.
3. Update the `Path().read_bytes()` test case to additionally validate the reduction in`isatty`/`ioctl` + `seek` calls from python#122111
4. Better diagnostic assertion messagess from @gpshead, so when the test fails have first information immediately available. Makes remote CI debugging much simpler.