fix(nm): Support portals to external interdependent workspaces

[larixer]

What's the problem this PR addresses?

Currently, nm installs that try to use portals to external interdependent workspaces fail, because nm linker tries to create self-reference symlinks in the target portal, however, these symlinks SHOULD NOT be created in this case, because --preserve-symlinks option must be used with Node to launch the project and self-references are supported automatically.

Fixes: #4179

How did you fix it?

The nm linker now skips self-reference symlinks creation attempts for external portals.

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.

[lehni]

thank you @larixer!