feat: honor nativeTheme.themeSource = 'dark' before creating BrowserWindow on Windows (#25373)

* fix: support 'dark' theme before creating windows.

BUILD.gn

@@ -673,6 +673,14 @@ source_set("electron_lib") {
   }
 
   sources += get_target_outputs(":electron_fuses")
+
+  if (is_win && enable_win_dark_mode_window_ui) {
+    sources += [
+      "shell/browser/win/dark_mode.cc",
+      "shell/browser/win/dark_mode.h",
+    ]
+    libs += [ "uxtheme.lib" ]
+  }
 }
 
 electron_paks("packed_resources") {