Collection: Make sure RunQuery does not access collection items

- Rename `QueryOptions` to `CollectionFilterOptions`.
- Create new class `CollectionQueryOptions` for passing options from model to `CollectionQuery`.
- Rename `Directory` to `CollectionDirectory`.

Fixes #1095

src/collection/collectionfilteroptions.h

@@ -0,0 +1,65 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2023, Jonas Kvinge <jonas@jkvinge.net>
+ *
+ * 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 COLLECTIONFILTEROPTIONS_H
+#define COLLECTIONFILTEROPTIONS_H
+
+#include <QString>
+
+#include "core/song.h"
+
+class CollectionFilterOptions {
+ public:
+
+  explicit CollectionFilterOptions();
+
+  // Filter mode:
+  // - use the all songs table
+  // - use the duplicated songs view; by duplicated we mean those songs for which the (artist, album, title) tuple is found more than once in the songs table
+  // - use the untagged songs view; by untagged we mean those for which at least one of the (artist, album, title) tags is empty
+  // Please note that additional filtering based on FTS table (the filter attribute) won't work in Duplicates and Untagged modes.
+  enum FilterMode {
+    FilterMode_All,
+    FilterMode_Duplicates,
+    FilterMode_Untagged
+  };
+
+  FilterMode filter_mode() const { return filter_mode_; }
+  int max_age() const { return max_age_; }
+  QString filter_text() const { return filter_text_; }
+
+  void set_filter_mode(const FilterMode filter_mode) {
+    filter_mode_ = filter_mode;
+    filter_text_.clear();
+  }
+  void set_max_age(const int max_age) { max_age_ = max_age; }
+  void set_filter_text(const QString &filter_text) {
+    filter_mode_ = FilterMode_All;
+    filter_text_ = filter_text;
+  }
+
+  bool Matches(const Song &song) const;
+
+ private:
+  FilterMode filter_mode_;
+  int max_age_;
+  QString filter_text_;
+};
+
+#endif  // COLLECTIONFILTEROPTIONS_H