donate-cpu: keep extracted package files inside the temp folder - #8973

unpack_package in tools/donate_cpu_lib.py only skips archive members whose name starts with '/' or '..', so a package tarball containing pkg/../../outside/x.c, or a symlink pkg/inc.h pointing at another directory followed by pkg/inc.h/x.c, writes source files outside work_path/temp when donate-cpu.py, test-my-pr.py or compare-valueflow-options.py unpack it on Python before 3.14 (3.14 refuses these by default, but the uncaught OutsideDestinationError aborts the run). Each member's destination, and the target of symlink and hardlink members, is now resolved with realpath and skipped unless it stays inside the temp folder, and filter='data' is passed where tarfile supports it; links that stay inside the package, such as include/a.h -> ../src/a.h, are still extracted. Added test_unpack_package_outside_temp, which fails on main with Python 3.9 and 3.12 and passes with the fix on 3.9, 3.12 and 3.14, and bumped CLIENT_VERSION to 1.4.1. I don't have Trac access, so could you create a ticket for this? I'll update the title once there is a number.