Qt: Use localized date/time formatting in a few more places

src/core/game_database.h

@@ -107,7 +107,7 @@ struct Entry
   std::string_view publisher;
   std::string_view compatibility_version_tested;
   std::string_view compatibility_comments;
-  u64 release_date;
+  u64 release_date; ///< Number of seconds since Epoch.
   u8 min_players;
   u8 max_players;
   u8 min_blocks;

src/duckstation-qt/achievementsettingswidget.cpp

@@ -199,10 +199,11 @@ void AchievementSettingsWidget::updateLoginState()
   {
     const u64 login_unix_timestamp =
       StringUtil::FromChars<u64>(Host::GetBaseStringSettingValue("Cheevos", "LoginTimestamp", "0")).value_or(0);
-    const QDateTime login_timestamp(QDateTime::fromSecsSinceEpoch(static_cast<qint64>(login_unix_timestamp)));
+    const QString login_timestamp = QtHost::FormatNumber(Host::NumberFormatType::ShortDateTime,
+                                                         static_cast<s64>(login_unix_timestamp));
     m_ui.loginStatus->setText(tr("Username: %1\nLogin token generated on %2.")
                                 .arg(QString::fromStdString(username))
-                                .arg(login_timestamp.toString(Qt::TextDate)));
+                                .arg(login_timestamp));
     m_ui.loginButton->setText(tr("Logout"));
   }
   else

src/duckstation-qt/gamesummarywidget.cpp

@@ -161,8 +161,11 @@ void GameSummaryWidget::populateUi(const std::string& path, const std::string& s
 
     QString release_info;
     if (entry->release_date != 0)
-      release_info =
-        tr("Released %1").arg(QDateTime::fromSecsSinceEpoch(entry->release_date, QTimeZone::utc()).date().toString());
+    {
+      const QString date = QDateTime::fromSecsSinceEpoch(static_cast<qint64>(entry->release_date), QTimeZone::utc())
+                             .toString(QtHost::GetApplicationLocale().dateFormat());
+      release_info = tr("Released %1").arg(date);
+    }
     if (entry->min_players != 0)
     {
       if (!release_info.isEmpty())

src/duckstation-qt/qthost.cpp

@@ -2217,7 +2217,7 @@ QString QtHost::FormatNumber(Host::NumberFormatType type, s64 value)
       }
       break;
 
-        DefaultCaseIsUnreachable();
+      DefaultCaseIsUnreachable();
     }
 
     ret = QDateTime::fromSecsSinceEpoch(value, QTimeZone::utc()).toLocalTime().toString(format);

src/duckstation-qt/setupwizarddialog.cpp

@@ -672,10 +672,11 @@ void SetupWizardDialog::updateAchievementsLoginState()
   {
     const u64 login_unix_timestamp =
       StringUtil::FromChars<u64>(Host::GetBaseStringSettingValue("Cheevos", "LoginTimestamp", "0")).value_or(0);
-    const QDateTime login_timestamp(QDateTime::fromSecsSinceEpoch(static_cast<qint64>(login_unix_timestamp)));
+    const QString login_timestamp = QtHost::FormatNumber(Host::NumberFormatType::ShortDateTime,
+                                                         static_cast<s64>(login_unix_timestamp));
     m_ui.loginStatus->setText(tr("Username: %1\nLogin token generated on %2.")
                                 .arg(QString::fromStdString(username))
-                                .arg(login_timestamp.toString(Qt::TextDate)));
+                                .arg(login_timestamp));
     m_ui.loginButton->setText(tr("Logout"));
   }
   else