Add support for ambient capabilities
Add support for ambient capabilities

Linux kernel 4.3 and later supports "ambient capabilities" which are the
only way to pass capabilities to containers running as a non root uid.

Previously there was no way to allow containers not running as root
capabilities in a useful way.

Fix #8460

Signed-off-by: Justin Cormack <af64ee19f04db9509cb02b0e470e11e5402ef9b3@docker.com>

docker/cli,riyazdf/cli,ashfall/cli,redpanda/cli,e11137/cli,docker/cli,dnephin/cli,thaJeztah/cli,cpuguy83/cli,riyazdf/cli,Zebrilee/cli,e11137/cli,thaJeztah/cli,allencloud/cli,cpuguy83/cli,Zebrilee/cli,dnephin/cli,ashfall/cli,redpanda/cli,allencloud/cli