common: move to modules, move some files out, modules: adjust dir structure

modules/nixos/programs/gaming.nix

@@ -0,0 +1,28 @@
+{ inputs, config, pkgs, ... }:
+
+let
+  nixpkgs-unstable = import inputs.nixpkgs-unstable {
+    system = "${pkgs.system}";
+    config.allowUnfree = true;
+  };
+in {
+  programs = {
+    gamemode.enable = true; # performance tuning for games
+    steam = {
+      enable = true;
+      extraCompatPackages = [ pkgs.proton-ge-bin ];
+    };
+  };
+  environment.systemPackages = with pkgs; [
+    gamescope # screen resolution controller for games that have bugs when changing resolution
+    alsa-oss # to fix minecraft audio jank
+    (prismlauncher.override {
+      # Change Java runtimes available to Prism Launcher
+      jdks = [
+        jdk8
+        nixpkgs-unstable.graalvmPackages.graalvm-oracle_17
+        inputs.nixpkgs-pin.legacyPackages.${pkgs.system}.graalvm-ce
+      ];
+    })
+  ];
+}