qt: Add helper to load font

src/qt/guiutil.cpp

@@ -272,6 +272,12 @@ bool hasEntryData(const QAbstractItemView *view, int column, int role)
     return !selection.at(0).data(role).toString().isEmpty();
 }
 
+void LoadFont(const QString& file_name)
+{
+    const int id = QFontDatabase::addApplicationFont(file_name);
+    assert(id != -1);
+}
+
 QString getDefaultDataDirectory()
 {
     return boostPathToQString(GetDefaultDataDir());