Build-arg local env variable pass-through

[ningziwen]

What is the problem you're trying to solve?. Similar to https://github.com/runfinch/finch/issues/35, build-arg in finch build is not supporting local env variable pass-through while Docker has this support.

Added draft failed e2e tests.

Describe the feature you'd like Allow local env variable pass-through for build-arg.

[estesp]

Now that #158 is merged and we have the framework for dealing with this related to -e/--env, should we solve this in a similar way?

[ningziwen]

@estesp Yes. Let me know if you want to collaborate it.

[chews93319]

As an additional update, the PR #1072 addressed cli parsing for other command names than build, but certainly clarifies why build does not utilize the helper functions for -e, --env, or --env-file arguments. The incremental change of 1072 sets the stage for more command specific flag handling and inclusion of separate helper functions like the environment variable flags.