* Containerd: download containerd from upstream instead of using distro specific packages
split runc download to separate role
make bootstrap-os role deploy container-selinux and seccomp libraries
clean up package manager provided containerd
move variables to docker role that are no longer common with containerd
* Containerd: make molecule testing more relevant
* replace ubuntu18 with ubuntu20
* add centos8 and debian11 to molecule tests
* run kubernetes/preinstall role to ensure relevancy
of test including dependency packages
* CI: adjust test scenarios for downloaded containerd
Kubespray deployment failed when using containerd backend on nodes that apparmor was not installed or previously removed. This PR ensure apparmor is installed by adding it into required_pkgs var.
On Debian 11, `ipset` just recommend `iptables` so on the system that apt is configured with `APT::Install-Recommends "0";` iptables will not install automatically.
