overlays: Move the Steam overlay into its own file

overlays/steam.nix

@@ -0,0 +1,39 @@
+pkgs: final: prev:
+
+# TODO: Replace with the commented out version below
+let
+  buildFHSUserEnvBubblewrap = prev.callPackage ../packages/build-support/build-fhs-userenv-bubblewrap {};
+  steamPackages = lib.dontRecurseIntoAttrs (prev.callPackage ../packages/games/steam {
+    buildFHSUserEnv = buildFHSUserEnvBubblewrap;
+  });
+in {
+  buildFHSUserEnvBubblewrap = buildFHSUserEnvBubblewrap;
+  steamPackages = steamPackages;
+  steam = steamPackages.steam-fhsenv.override {
+    extraPkgs = pkgsx: with pkgsx; [ gamemode ];
+  };
+
+   #(final: prev:
+   #  let
+   #    # NOTE: This is a really messy solution
+   #    buildFHSUserEnvBubblewrap = prev.callPackage ../packages/build-support/build-fhs-userenv-bubblewrap {};
+   #  in {
+   #    steamPackages = prev.steamPackages.override {
+   #      buildFHSUserEnv = buildFHSUserEnvBubblewrap;
+   #      # Include gamemode in the FHS
+   #      #extraPkgs = (pkgs: with pkgs; [ gamemode ]);
+   #    };
+
+   #    steam = prev.steamPackages.steam-fhsenv.overrideAttrs (old: {
+   #      specifyHomeDirs = true;
+   #      chdirTo = "/home/$USER";
+   #    });
+   #   #steam = final.steamPackages.steam-fhsenv.override {
+   #   #  extraPkgs = pkgs: with pkgs; [ gamemode ];
+   #   #};
+   #    steam-run = final.steam.run;
+   #    steam-run-native = (final.steam.override {
+   #      nativeOnly = true;
+   #    });
+   #    steamcmd = final.steamPackages.steamcmd;
+   #  })