opensplat: init at 1.1.2

[jcaesar]

Description of changes

This PR adds OpenSplat, "A free and open source implementation of 3D gaussian splatting written in C++, focused on being portable, lean and fast.": https://github.com/pierotofy/opensplat

Notes for this PR:

• To check basic functionality:

  nix shell nixpkgs#python311Packages.opensfm github:NixOS/nixpkgs/pull/305300/head#opensplatWithCuda
  git clone https://github.com/mapillary/OpenSfM/ opensfm
  cd opensfm
  git checkout 5e854bb43f046ac9277dcfc7a891bab8587f070f
  cd data/berlin # this is example data for structure from motion, not gaussian splatting, so the result will be pretty bad, i.e. only viewable from a narrow angle
  opensfm_run_all .
  ls images/* | save -f image_list.txt
  opensplat .
  # open https://antimatter15.com/splat/?url=https://splat.uav4geo.com/banana.splat and drag and drop the resulting splat.ply file onto it (sorry, I don't know a better way). rotate around to find a good angle
  

• There's also a rocm/hip backend (and there will be a metals backend in the next release, it seems), but I don't have hardware, experience, or examples (there isn't a single package in nixpkgs uses cmake+hip+torch) to work with for that.
• I have contributed the patch upstream
• This is my second PR, the first hasn't been accepted yet. If there's a general issue with style, please do tell

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/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 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
• Fits CONTRIBUTING.md.

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[jcaesar]

Result of nixpkgs-review pr 305300 run on x86_64-linux 1

2 packages built:

• opensplat
• opensplatWithCuda

[Aleksanaa]

Builds, but I don't think I can test it. Merging anyway