Add type trait tests for sf::SoundFileWriter

Other Audio module types get this same treatment so we ought to
also have a .test.cpp for this header.

test/Audio/SoundFileWriter.test.cpp

@@ -0,0 +1,10 @@
+#include <SFML/Audio/SoundFileWriter.hpp>
+
+#include <type_traits>
+
+static_assert(!std::is_constructible_v<sf::SoundFileWriter>);
+static_assert(!std::is_copy_constructible_v<sf::SoundFileWriter>);
+static_assert(std::is_copy_assignable_v<sf::SoundFileWriter>);
+static_assert(!std::is_nothrow_move_constructible_v<sf::SoundFileWriter>);
+static_assert(std::is_nothrow_move_assignable_v<sf::SoundFileWriter>);
+static_assert(std::has_virtual_destructor_v<sf::SoundFileWriter>);

test/CMakeLists.txt

@@ -139,6 +139,7 @@ set(AUDIO_SRC
     Audio/SoundBufferRecorder.test.cpp
     Audio/SoundFileFactory.test.cpp
     Audio/SoundFileReader.test.cpp
+    Audio/SoundFileWriter.test.cpp
     Audio/SoundRecorder.test.cpp
     Audio/SoundSource.test.cpp
     Audio/SoundStream.test.cpp