chore(ci): trace target directory content for cache troubleshooting

[daniellavoie]

#153 reported a suspicious cache usage increase.

This PR introduces a new step in the build process to output the content of the target directory after the build. This will help investigate if something is wrong builds after builds.

I ran multiple builds with this change and couldn't observe any file change or file increase from the same commits.

Here is an example of the new step in action: https://github.com/daniellavoie/Ambient/actions/runs/4257943674/jobs/7408628309