SoundPlayer: Load cover image from music files

When the visualization is set to "Album Cover", the player will now try
to load the embedded image. On failure, it defaults to a "Cover" image
file in the directory.

In Player::play_file_path, file_name_changed now needs to be executed
after that the loader have been set, to get the correct image.

Userland/Applications/SoundPlayer/Player.h

@@ -11,6 +11,7 @@
 #include "Playlist.h"
 #include "PlaylistWidget.h"
 #include <AK/RefPtr.h>
+#include <LibAudio/GenericTypes.h>
 #include <LibAudio/Sample.h>
 
 class Player {
@@ -75,6 +76,8 @@ public:
     virtual void total_samples_changed(int) = 0;
     virtual void sound_buffer_played(FixedArray<Audio::Sample> const&, [[maybe_unused]] int sample_rate, [[maybe_unused]] int samples_played) = 0;
 
+    Vector<Audio::PictureData> const& pictures() const;
+
 protected:
     void done_initializing()
     {