[Request]: Support seccomp inside the container

### Feature or enhancement request details

Currently seccomp seems to be not available inside the container runtime, leading programs that use it to fail executing.

Here #1628 pacman fails to initialize a sandbox to install packages.

From experience, Podman supports this and I think Docker does as well, so it would be nice to reach feature parity.

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Start by reproducing the pacman sandbox failure described in issue #1628 and trace how the container runtime currently handles syscall filtering. Compare the relevant behavior with Podman or Docker, then determine the runtime changes and validation needed for seccomp-using programs to execute successfully.

Written by the indexing model from the issue text.