Restore detailed Nix CLI version (backport #12498)

[mergify]

... as intended.

Requirements:

• don't build fresh libraries for each git commit
• have git commit in the CLI

Bug:

• echo ${version} went into the wrong file
  => use the fact that it's a symlink, not just for reading but also for writing.

Motivation

Context

• Review commit by commit

• Refines the implementation of Rewrite build system in Meson #2503

---

Add 👍 to pull requests you find important.

The Nix maintainer team uses a GitHub project board to schedule and track reviews.

---

This is an automatic backport of pull request #12498 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of bba4e6b has failed:

On branch mergify/bp/2.26-maintenance/pr-12498
Your branch is up to date with 'origin/2.26-maintenance'.

You are currently cherry-picking commit bba4e6b06.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   src/libstore/globals.cc
	modified:   src/libstore/globals.hh
	modified:   src/nix/meson.build
	modified:   src/nix/package.nix

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/nix/main.cc

Cherry-pick of 3556f6b has failed:

On branch mergify/bp/2.26-maintenance/pr-12498
Your branch is ahead of 'origin/2.26-maintenance' by 1 commit.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 3556f6bf4.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   src/libcmd/package.nix
	modified:   src/libexpr-c/package.nix
	modified:   src/libexpr-test-support/package.nix
	modified:   src/libexpr-tests/package.nix
	modified:   src/libexpr/package.nix
	modified:   src/libfetchers-tests/package.nix
	modified:   src/libfetchers/package.nix
	modified:   src/libflake-c/package.nix
	modified:   src/libflake-tests/package.nix
	modified:   src/libflake/package.nix
	modified:   src/libmain-c/package.nix
	modified:   src/libmain/package.nix
	modified:   src/libstore-c/package.nix
	modified:   src/libstore-test-support/package.nix
	modified:   src/libstore-tests/package.nix
	modified:   src/libstore/package.nix
	modified:   src/libutil-c/package.nix
	modified:   src/libutil-test-support/package.nix
	modified:   src/libutil-tests/package.nix
	modified:   src/libutil/package.nix
	modified:   src/nix/package.nix
	modified:   tests/functional/package.nix

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   packaging/dependencies.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