Add go-install arguments and env vars

[wagoodman]

This add the ability to pass arguments/flags to go install as well as set specific environment variables, for example:

  - name: skopeo
    version:
      want: v1.12.0
    method: go-install
    with:
      module: github.com/containers/skopeo
      entrypoint: cmd/skopeo
      args:
        - "-tags"
        - containers_image_openpgp
      env:
        - CGO_ENABLED=0
        - GO_DYN_FLAGS=""