mir: init at 2.11.0

[OPNA2608]

Description of changes

Based on / obsoletes / closes #207534

• Mir 2.11.0 (whether that'll work with Lomiri remains to be seen, as discussed in mir: init at 2.11.0 #207534 (comment))
  • Pulls in an upstream PR I made which fixes some path concatenation problems
  • Docs build, and have impure build date details patched out
  • Tests enabled and passing on my x86_64-linux & aarch64-linux systems
    • I had to disable 3 tests. I don't understand why they fail inside the build environment but work when run interactively. Possibly something worth looking into.
  • Marked the example mir-shell Wayland session so login managers can pick it up
    • It's just a basic example, needs vanilla-dmz with vanilla-dmz: Expose themes under DMZ-{White,Black} names #208487 on XCURSOR_PATH or changing the default icon theme to an installed one, might be useful enough for some testing/debugging though
• Moving eglexternalplatform out of egl-wayland doesn't seem necessary for building Mir (at least 2.x) while bloating the rebuild count, so it's not being done in this PR

The example shell can be tested under a running X11/Wayland session via miral-app -kiosk -terminal <term>, with <term> being a terminal that works on Wayland. (kiosk mode is the only option that's semi-functional without requiring some configuration & additional packages)

@onny, letting you know that I've left you as co-author of the commit & co-maintainer of the package.

Things done

• 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.

[onny]

Result of nixpkgs-review pr 211193 run on x86_64-linux 1

1 package built:

• mir

[onny]

Nice work at @OPNA2608 , thank you!