Ability to use Dockerfile / container runtime in plugins

[davidferlay]

Current

• Plugin commands can only be written as golang
• Plugin commands are programs directly executed on host, not runnable in container environement

Expected

• Plugin commands should be able to be executed in container environement, using a specified Dockerfile, as regular local action do
• This will allow plugin commands to be written in any language and executed in a container

[lexbritvin]

Merged