darwin: add darwin-aliases.nix

[reckenrode]

Description of changes

Darwin needs a way to deprecate and move packages in the darwin scope. This is needed to support transitioning to upstream packages for libiconv and icu. It’s also useful for moving things out of darwin to by-name.

This PR also moves two packages to darwin-aliases.nix:

• builder (moved from an ad hoc alias)
• moltenvk (moved to by-name)

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[reckenrode]

If I did this right, there shouldn’t be any rebuilds.

[reckenrode]

I dropped the MoltenVK move. I’ll do it as part of the 1.2.8 update once this is merged (or post update depending on timing). It was causing the by-name check to fail due to using apple_sdk_11_0.callPackage. Unfortunately, switching it to use overrideSDK would cause rebuilds (defeating the goal of doing this PR without rebuilds).

[ghost]

LGTM.

testing:

• added alias with a throw and it threw
• added alias to another package and got other package
• ran meta checks locally and validated that the aliases were not used.

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/darwin-updates-news/42249/5