Add support for detecting and controlling the platform

[tfoote]

docker supports multi-arch capabilities. Oddly it's a sticky option. If you last ran an image with one platform it will invoke future elements.

The side effecting isn't good.

It would be good to take a --platform argument and execute it . But otherwise use the system native platform.

It would probably need to detect the current default somehow to optionally override it to keep it commands repeatable.