Fix #9386: compilers failing to compile with LTO by using variants instead of new + unique_ptr

With std::variant all memory can be figured out at compile time, so the compiler needs to keep track of fewer elements. It also saves out a unique_ptr and its memory management, over a slight impact for resolving a setting.

src/table/settings/misc_settings.ini

@@ -20,7 +20,7 @@ extern bool _allow_hidpi_window;
 #define WITHOUT_COCOA
 #endif
 
-static const SettingTable _misc_settings{
+static const SettingVariant _misc_settings[] = {
 [post-amble]
 };
 [templates]