Turbopack: Generalize `ImportedBinding` effect creation to avoid as much special-casing of SimpleAssignTarget (#81653)
There was some logic here that checked for the existence of `SimpleAssignTarget`, and using that to bail out of `visit_ident`. That doesn't scale well to pattern assignments, but it turns out that we don't need to bail out, we just need to fix the codegen.
Without this, https://github.com/vercel/next.js/pull/81654 breaks the test cases.