Add option to set envs in BuildMixin.build function

I am creating this as an issue/enhancement as I did not see an option for this elsewhere. It would be nice to have a possibility to set environment variables during the image building and/or reference an env file. Talking about this build function here: https://podman-py.readthedocs.io/en/latest/podman.domain.images_manager.html#podman.domain.images_manager.ImagesManager.build
Afaik podman itself provides the option to set envs in the image build process while podman python only allows buildargs which are not getting passed to the image itself.

Thanks!

Start with the documented ImagesManager.build entry point linked in the issue and inspect how BuildMixin.build currently handles buildargs. Compare the available Podman image-build options for environment variables and env files. Done means the Python binding can express the requested environment settings during image building, with behavior matching the underlying Podman option.

Written by the indexing model from the issue text.