modules/performance: add ability to byte compile lua configuration files

This commit adds support for byte compiling lua configuration files.
It's enabled by default (if byte compiling is enabled at all) and can be
disabled with `performance.byteCompileLua.configs` toggle.

To implement this feature `extraFiles.<name>.finalSource` internal
read-only option is introduced. `source` option cannot be used because
it's user configurable. In order to access the values of the
`performance.byteCompileLua` options, parent config is added to
specialArgs of extraFiles submodule. Then the usages of `source` option
changed to `finalSource` in all relevant places (filesPlugin and
wrappers).

Added more helpers for various cases of byte compiling:

* `byteCompileLuaFile` byte compiles lua file
* `byteCompileLuaHook` is a setup hook that byte compiles all lua files
* `byteCompileLuaDrv` overrides derivation by adding byteCompileLuaHook
  to it

Added tests to validate that extraFiles specified by various methods are
handled correctly. Added a separate home-manager test, that is intended
to validate that extraFiles propagated to wrapper modules are correctly
byte compiled.

tests/modules/hm-extra-files-byte-compiling.nix

@@ -0,0 +1,104 @@
+{
+  nixvim,
+  pkgs,
+  home-manager,
+}:
+let
+  config = {
+    home = {
+      username = "nixvim";
+      homeDirectory = "/invalid/dir";
+      stateVersion = "24.05";
+    };
+
+    programs.nixvim = {
+      enable = true;
+
+      performance.byteCompileLua.enable = true;
+
+      extraFiles = {
+        "extra-files/test1.lua".text = "vim.opt.tabstop = 2";
+        "extra-files/test2.lua".source = builtins.toFile "file_source.lua" "vim.opt.tabstop = 2";
+        "extra-files/test3.lua".source = pkgs.writeText "test3.lua" "vim.opt.tabstop = 2";
+        "extra-files/test.vim".text = "set tabstop=2";
+        "extra-files/test.json".text = builtins.toJSON { a = 1; };
+      };
+
+      files = {
+        "files/test.lua".opts.tabstop = 2;
+        "files/test.vim".opts.tabstop = 2;
+      };
+    };
+  };
+
+  homeFilesByteCompilingEnabled =
+    (home-manager.lib.homeManagerConfiguration {
+      inherit pkgs;
+
+      modules = [
+        nixvim.homeManagerModules.nixvim
+        config
+        { programs.nixvim.performance.byteCompileLua.configs = true; }
+      ];
+    }).config.home-files;
+
+  homeFilesByteCompilingDisabled =
+    (home-manager.lib.homeManagerConfiguration {
+      inherit pkgs;
+
+      modules = [
+        nixvim.homeManagerModules.nixvim
+        config
+        { programs.nixvim.performance.byteCompileLua.configs = false; }
+      ];
+    }).config.home-files;
+in
+pkgs.runCommand "home-manager-extra-files-byte-compiling" { } ''
+  is_binary() {
+      ! grep -qI . "$1"
+  }
+  test_byte_compiled() {
+      if ! is_binary "$home_files/.config/nvim/$1"; then
+          echo "File $1 is expected to be byte compiled, but it's not"
+          exit 1
+      fi
+  }
+  test_not_byte_compiled() {
+      if is_binary "$home_files/.config/nvim/$1"; then
+          echo "File $1 is not expected to be byte compiled, but it is"
+          exit 1
+      fi
+  }
+
+  # Test directory with extraFiles byte compiling enabled
+  home_files="${homeFilesByteCompilingEnabled}"
+
+  echo "Testing home-files with extraFiles byte compiling enabled"
+
+  # extraFiles
+  test_byte_compiled extra-files/test1.lua
+  test_byte_compiled extra-files/test2.lua
+  test_byte_compiled extra-files/test3.lua
+  test_not_byte_compiled extra-files/test.vim
+  test_not_byte_compiled extra-files/test.json
+  # files
+  test_byte_compiled files/test.lua
+  test_not_byte_compiled files/test.vim
+
+  # Test directory with extraFiles byte compiling disabled
+  home_files="${homeFilesByteCompilingDisabled}"
+
+  echo "Testing home-files with extraFiles byte compiling disabled"
+
+  # extraFiles
+  test_not_byte_compiled extra-files/test1.lua
+  test_not_byte_compiled extra-files/test2.lua
+  test_not_byte_compiled extra-files/test3.lua
+  test_not_byte_compiled extra-files/test.vim
+  test_not_byte_compiled extra-files/test.json
+  # files
+  test_not_byte_compiled files/test.lua
+  test_not_byte_compiled files/test.vim
+
+  touch $out
+''