Add filtering of numerical cols to collection

CollectionFilterWidget: Updated the tooltip, to reflect the changes.
CollectionQuery: Add parsing for SQL operators and insert right SQL
"where" searches.
Song: Add list of numerical columns
playlistfilterparser.cpp/FilterParser: move time and rating parsing
functions to new file:
searchparserutils.cpp: Contains common code used to parse search terms
in playlist and collection filters.

src/utilities/searchparserutils.h

@@ -0,0 +1,33 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2019-2023, Jonas Kvinge <jonas@jkvinge.net>
+ * Copyright 2023, Daniel Ostertag <daniel.ostertag@dakes.de>
+ *
+ * Strawberry is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Strawberry is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef SEARCHPARSERUTILS_H
+#define SEARCHPARSERUTILS_H
+
+#include <QString>
+
+namespace Utilities {
+
+int ParseSearchTime(const QString &time_str);
+float ParseSearchRating(const QString &rating_str);
+
+}  // namespace Utilities
+
+#endif  // SEARCHPARSERUTILS_H