Support using --build-arg-file for building / supplying a build arg file to build a container.

[cdrage]

Is your feature request related to a problem? Please describe

Got this request IRL during a Podman meetup.

Someone asked how they could supply a build arg file for building a container.

And we don't at the moment..

Example:

podman build --build-arg-file foobar.env

Which is very beneficial with regards to building something that has multiple environment variables.

Describe the solution you'd like

Be able to provide a build arg file when building.

Describe alternatives you've considered

No response

Additional context

No response