nixos/containers: new registries.settings option, deprecate others

[minijackson]

Those options mapped to the deprecated V1 format, and didn't allow using the newer format.

If any of the older options are used, a warning is displayed, and the generated registries.conf file follows the old V1 format.

For more information about the new format, see https://github.com/containers/image/blob/main/docs/containers-registries.conf.5.md

Tested by building the /etc/containers/registries.conf file, and checked that I could match both the old and the newer format.

Examine the first commit to ignore formatting changes.

cc @NixOS/podman

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• 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/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 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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[mhutter]

Ah yes, exactly as I envisioned