Reimplement (C++23) deprecated std::aligned_storage (#2680)

Use boost::aligned_storage instead of std::.

The latter is deprecated in C++23.

---------

Co-authored-by: Ed Catmur <edward.catmur@mavensecurities.com>

include/boost/beast/core/detail/type_traits.hpp

@@ -10,6 +10,7 @@
 #ifndef BOOST_BEAST_DETAIL_TYPE_TRAITS_HPP
 #define BOOST_BEAST_DETAIL_TYPE_TRAITS_HPP
 
+#include <boost/type_traits/aligned_storage.hpp>
 #include <boost/type_traits/make_void.hpp>
 #include <type_traits>
 #include <new>
@@ -64,7 +65,7 @@ struct aligned_union
     std::size_t constexpr alignment_value =
         max_alignof<Ts...>();
 
-    using type = typename std::aligned_storage<
+    using type = typename boost::aligned_storage<
         (Len > max_sizeof<Ts...>()) ? Len : (max_sizeof<Ts...>()),
             alignment_value>::type;
 };

include/boost/beast/websocket/detail/decorator.hpp

@@ -12,6 +12,7 @@
 
 #include <boost/beast/websocket/rfc6455.hpp>
 #include <boost/core/exchange.hpp>
+#include <boost/type_traits/aligned_storage.hpp>
 #include <boost/type_traits/make_void.hpp>
 #include <algorithm>
 #include <memory>
@@ -62,7 +63,7 @@ class decorator
     {
         void* p_;
         void (*fn_)();
-        typename std::aligned_storage<
+        typename boost::aligned_storage<
             sizeof(exemplar),
             alignof(exemplar)>::type buf_;
     };