zplug: update the output path (#228284)

* zplug: update the output path

This is a breaking change because the old behavior pollutes the nix profile root
dir with all files in https://github.com/zplug/zplug and needs to be fixed.

I created a corresponding PR in the home manager repo
https://github.com/nix-community/home-manager/pull/3922. For non HM users, they
will need to update their dependency on `${pkgs.zplug}/init.zsh` to `${pkgs.zplug}/share/zplug/init.zsh`.

* Only add necessary files to $out/share/zplug. Also add the zplug man pages

The LICENSE file is not in the 2.4.2 tag and there's not a release after that. I
would skip adding the license $out/licenses/zplug in this commit.

Reference: https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=zplug

nixos/doc/manual/release-notes/rl-2305.section.md

···
 - The `pnpm` package has be updated to from version 7.29.1 to version 8.1.1 and Node.js 14 support has been discontinued (though, there are workarounds if Node.js 14 is still required)
   - Migration instructions: ["Before updating pnpm to v8 in your CI, regenerate your pnpm-lock.yaml. To upgrade your lockfile, run pnpm install and commit the changes. Existing dependencies will not be updated; however, due to configuration changes in pnpm v8, some missing peer dependencies may be added to the lockfile and some packages may get deduplicated. You can commit the new lockfile even before upgrading Node.js in the CI, as pnpm v7 already supports the new lockfile format."](https://github.com/pnpm/pnpm/releases/tag/v8.0.0)
 
+- The `zplug` package changes its output path from `$out` to `$out/share/zplug`. Users should update their dependency on `${pkgs.zplug}/init.zsh` to `${pkgs.zplug}/share/zplug/init.zsh`.
+
 ## Other Notable Changes {#sec-release-23.05-notable-changes}
 
 <!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->

pkgs/shells/zsh/zplug/default.nix

···
   dontPatch = true;
 
   installPhase = ''
-    mkdir -p $out
-    cp -r $src/* $out/
+    mkdir -p $out/share/zplug
+    cp -r $src/{autoload,base,bin,init.zsh,misc} $out/share/zplug/
+    mkdir -p $out/share/man
+    cp -r $src/doc/man/* $out/share/man/
   '';
 
   meta = with lib; {