Improve album cover searching and cover manager, use HttpStatusCodeAttribute and QSslError for services

- Improve album cover manager
- Change art_automatic and art_manual to QUrl
- Refresh collection album covers when new album covers are fetched
- Fix automatic album cover searching for local files outside of the collection
- Make all Json services check HttpStatusCodeAttribute
- Show detailed SSL errors for Subsonic, Tidal and Qobuz

src/tidal/tidalstreamurlrequest.h

@@ -22,7 +22,9 @@
 
 #include "config.h"
 
+#include <QObject>
 #include <QString>
+#include <QStringList>
 #include <QUrl>
 
 #include "core/song.h"
@@ -60,12 +62,15 @@ class TidalStreamURLRequest : public TidalBaseRequest {
   void StreamURLReceived();
 
  private:
+  void Error(const QString &error, const QVariant &debug = QVariant());
+
   TidalService *service_;
   QNetworkReply *reply_;
   QUrl original_url_;
   int song_id_;
   int tries_;
   bool need_login_;
+  QStringList errors_;
 
 };