[Feature Request] Nix package

[AdrienLemaire]

Is your feature request related to a problem? Please describe.
For Nix and NixOS users, a nix package is necessary for installation

Describe the solution you'd like
Following nixpkgs conventions, we should create a file package.nix.
Here's a template to get started with:

{ lib
, stdenv
, fetchFromGitHub
}:

stdenv.mkDerivation rec {
  pname = "fvm";
  version = "3.2.1";

  src = fetchFromGitHub {
    owner  = "leoafarias";
    repo   = "fvm";
    rev    = "v${version}";
    sha256 = "06ywxznch1r9fb6598i632rz207vw3ncg9g1yabarrnj3920kfwb";
  };

  phases = [ "installPhase" ];
  installPhase = ''
    mkdir -p $out/bin
    # If we fetched a single binary named fvm:
    cp fvm-${version} $out/bin/fvm
    chmod +x $out/bin/fvm
  '';

  meta = with lib; {
    description = "Flutter Version Management: CLI to manage multiple Flutter SDK versions";
    homepage    = "https://github.com/leoafarias/fvm";
    license     = licenses.mit;
    maintainers = [ maintainers.yourName ];
    platforms   = platforms.all;
  };
}

Describe alternatives you've considered
I was considering creating the nix package myself, but being a new nixos user, I lack experience with it. Since fvm has a lot of pre-built packages for different platforms, I'm not sure what would be the best way to support them all in nix.

Additional context
Similar packages such as volta have their nix package and could be used as reference.