i3: 4.21.1 -> 4.22, i3-gaps: drop

[reedrw]

Description of changes

i3 has been updated to version 4.22, this version at long last merges the i3-gaps fork, which has been maintained in parallel for years. The former maintainer of i3-gaps has asked that package maintainers replace it with i3, as it will no longer be updated. i3-gaps users can safely move to upstream i3 without any changes in behavior, so I've replaced the i3-gaps package with an alias to i3.

Full release notes: https://github.com/i3/i3/blob/4.22/RELEASE-NOTES-4.22

Things done

i3 updated to 4.22, i3-gaps removed and replaced with an alias to i3 so peoples' configs aren't broken.

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 23.05 Release Notes (or backporting 22.11 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
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[reedrw]

This should also affect the module documentation and removed module assertion for the i3 module, but I'm not sure whether or not a separate PR is warranted.

[dasJ]

i3-gaps is still used in the polybar package which is now broken if aliases are disabled