Add Minecraft clients lunar-client and hmcl.

To play with my kids!

But really, I never got lunar-client working, but I did eventually get
hmcl working on Hypixel, and that's what really counts.

nalai/etc/nixos/configuration.nix

@@ -120,7 +120,7 @@
   programs.neovim.defaultEditor = true;
 
   nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
-    "spotify"
+    "lunar-client" "spotify"
   ];
 
   # List packages installed in system profile. To search, run:
@@ -137,7 +137,9 @@
     gimp-with-plugins
     git
     gnumake
+    hmcl
     keychain
+    lunar-client
     mosh
     mumble
     neovim