[Models] Use QCollator for natural, cached sorting (#7633)

* [Models] Use QCollator for natural, cached sorting

QString::localeAwareCompare rebuilds its collation data for every
comparison, and it compares numbers as text. Keep one QCollator per model,
enable numeric mode, and use it for the card name, set and user name sorts.

Add a test that sorts "Forest 1", "Forest 2", "Forest 10" through
DeckListSortFilterProxyModel and checks the natural order.

* [Models] Sort naturally under the C locale too

Numeric mode only takes effect through a real locale: under the C locale,
which headless CI processes run in, QCollator silently falls back to string
order and sorts "Forest 10" before "Forest 2". That made collator_sort_test
fail on every Linux leg while passing locally.

Add makeNaturalSortCollator(), which enables numeric mode and pins English
only when the process locale is the degenerate one, and build the models'
collators through it. Users with a real locale keep their own collation.

* [Models] Fix compile of natural sorting (QStringView mismatch)

* nit: initialize collators in member initializer lists

* nit: namespace makeNaturalSortCollator under NaturalSort

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/widgets/server/user/user_list_widget.cpp

@@ -16,6 +16,7 @@
 #include <QAbstractItemModel>
 #include <QApplication>
 #include <QByteArray>
+#include <QCollator>
 #include <QColor>
 #include <QContextMenuEvent>
 #include <QCursor>
@@ -55,6 +56,7 @@
 #include <QVariant>
 #include <QWidget>
 #include <QtGlobal>
+#include <libcockatrice/models/natural_sort_collator.h>
 #include <libcockatrice/settings/appearance_settings.h>
 #include <libcockatrice/utility/qt_utils.h>
 #include <qnamespace.h>
@@ -272,6 +274,11 @@ void UserListTWI::setOnline(bool online)
  */
 bool UserListTWI::operator<(const QTreeWidgetItem &other) const
 {
+    // QCollator caches the locale data, unlike QString::localeAwareCompare,
+    // which rebuilds it for every pair. The tree sorts one list at a time, so a
+    // single shared, immutable collator is enough.
+    static const QCollator collator = NaturalSort::makeNaturalSortCollator();
+
     // Sort by online/offline
     if (data(0, UserListRoles::Online) != other.data(0, UserListRoles::Online)) {
         return data(0, UserListRoles::Online).toBool();
@@ -287,8 +294,7 @@ bool UserListTWI::operator<(const QTreeWidgetItem &other) const
     for (const auto &userLevelEntry : userLevelWithNoOtherPrefOrder) {
         if (lhsUserLevelFlags.testFlag(userLevelEntry) &&
             lhsUserLevelFlags.testFlag(userLevelEntry) == rhsUserLevelFlags.testFlag(userLevelEntry)) {
-            return QString::localeAwareCompare(data(2, Qt::UserRole).toString(),
-                                               other.data(2, Qt::UserRole).toString()) < 0;
+            return collator.compare(data(2, Qt::UserRole).toString(), other.data(2, Qt::UserRole).toString()) < 0;
         } else if (lhsUserLevelFlags.testFlag(userLevelEntry) != rhsUserLevelFlags.testFlag(userLevelEntry)) {
             return lhsUserLevelFlags.testFlag(userLevelEntry) > rhsUserLevelFlags.testFlag(userLevelEntry);
         }
@@ -313,7 +319,7 @@ bool UserListTWI::operator<(const QTreeWidgetItem &other) const
     }
 
     // Sort by name
-    return QString::localeAwareCompare(data(2, Qt::UserRole).toString(), other.data(2, Qt::UserRole).toString()) < 0;
+    return collator.compare(data(2, Qt::UserRole).toString(), other.data(2, Qt::UserRole).toString()) < 0;
 }
 
 UserListWidget::UserListWidget(TabSupervisor *_tabSupervisor,