crun: use instead of runc for lower memory overhead

[paralin]

crun is a much lighter weight version of runc written in C instead of Go.

Switch to using crun instead of runc for containerd & docker.

[paralin]

Hey @tianyuanhao I'll try it out tonight, thanks for the reminder!

[paralin]

@tianyuanhao is it possible to add a config file for containerd to change it to use CRUN, as opposed to the symlink? I'll add my reviewed-by to the patch in the mailing list but they might not like the symlink approach

[paralin]

@tianyuanhao I submitted my reviewed-by on the mailing list and have merged your commit into the skiffos tree.

I'll try now to switch runc for crun on all skiffos default configs. Thanks!

[paralin]

This is now integrated.