Instead of having every test helper binary in its own directory, let's
use /tests/cmd/_bin as a destination directory.
This allows for simpler setup/cleanup.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
The following commands are moved from `contrib/cmd` to `tests/cmd`:
- fs-idmap
- pidfd-kill
- recvtty
- remap-rootfs
- sd-helper
- seccompagent
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>