ryujinx: remove to point users towards ryubing

[ghost]

Removes Ryujinx and aliases to an error which informs users of the ryubing package. This is done on the grounds of Ryujinx not having an upstream anymore and development moving onto ryubing and users should be pointed to the healthy upstream source.

This is not done on any legal grounds, which was discussed in #425950 which would encompass both packages and the consensus from the Ryujinx package maintainers in nixpkgs is not to merge.

I'm not sure if this should also have a corresponding release notes entry so I need confirmation on that.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

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