buildx/driver/docker-container
Tonis Tiigi 4c1621cccd store snapshot of config files on create
Files can be reused when container needs to be booted again.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
..
driver.go store snapshot of config files on create
factory.go docker-container: support --driver-opt cgroup-parent=...