Nested variables interpolation in compose files

[gilbsgilbs]

- What I did

Fix nested variables interpolation in compose files which should be allowed as per compose specification.

- How I did it

Use compose-go for variables interpolation in compose files instead of the current implementation.

I've also considered copying the code from compose-go as it is very similar to the existing implementation (and was probably initially copied from this project), but I assumed it would be better to use the reference implementation. Feel free to tell me if you don't want to add this new dependency.

- How to verify it

Run the test suite with/without the fix, or use the repro described in #4265

- Description for the changelog

Fix nested variables interpolation in compose files.

- A picture of a cute animal (not mandatory but encouraged)

Fixes #4265

[gilbsgilbs]

I just rebased this PR as apparently this is still an issue: https://github.com/docker/cli/issues/4265#issuecomment-2579177595 .