mir: 2.17.2 -> 2.18.2

[OPNA2608]

Description of changes

• nixfmt the common file
• update the unpinned mir to 2.18.2
• add Miriway and Miracle WM's VM tests as tests for Mir, so I don't need to manually invoke OfBorg for them all the time

Draft because it's brand new, and miracle-wm is not compatible with it yet: miracle-wm-org/miracle-wm#243
Addressed by new release, included in PR: https://github.com/miracle-wm-org/miracle-wm/releases/tag/v0.3.6

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/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 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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