Pass environment variables to asdf-exec first

What does this merge request do and why?

While asdf env can handle environment variables in its command, mise exec cannot. We can pass them in first instead.

How to set up and validate locally

1. Enable duo workflow

   $ gdk config set duo_workflow.enabled true

2. Reconfigure

   gdk reconfigure

3. duo-workflow-executor should be built successfully!

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.