EvalState::realiseContext(): Allow access to the entire closure (backport #12045)

[mergify]

Motivation

When doing IFD, we should allow access to the entire closure of the store paths built by the derivation, not just the top-level paths.

Fixes #11030.

Context

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This is an automatic backport of pull request #12045 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 08361f0 has failed:

On branch mergify/bp/2.25-maintenance/pr-12045
Your branch is up to date with 'origin/2.25-maintenance'.

You are currently cherry-picking commit 08361f031.
  (fix conflicts and run "git cherry-pick --continue")
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  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   src/libexpr/eval.hh
	modified:   src/libexpr/primops.cc
	modified:   tests/functional/import-from-derivation.sh

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/libexpr/eval.cc
	both modified:   tests/functional/import-from-derivation.nix

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally