Revise classes startup sequence

1. Initialize Logger class earlier so that it can record messages from other classes (for
   debugging purpose).
2. Deprioritize WebUI port adjustment. It is not a high priority in here.
3. Slightly deprioritize file logger initialization.

src/app/application.cpp

@@ -147,6 +147,8 @@ Application::Application(int &argc, char **argv)
     QPixmapCache::setCacheLimit(PIXMAP_CACHE_SIZE);
 #endif
 
+    Logger::initInstance();
+
     const auto portableProfilePath = Path(QCoreApplication::applicationDirPath()) / DEFAULT_PORTABLE_MODE_PROFILE_DIR;
     const bool portableModeEnabled = m_commandLineArgs.profileDir.isEmpty() && portableProfilePath.exists();
 
@@ -158,35 +160,34 @@ Application::Application(int &argc, char **argv)
 
     m_instanceManager = new ApplicationInstanceManager(Profile::instance()->location(SpecialFolder::Config), this);
 
-    Logger::initInstance();
     SettingsStorage::initInstance();
     Preferences::initInstance();
 
     initializeTranslation();
 
-    if (m_commandLineArgs.webUiPort > 0) // it will be -1 when user did not set any value
-        Preferences::instance()->setWebUiPort(m_commandLineArgs.webUiPort);
-
     connect(this, &QCoreApplication::aboutToQuit, this, &Application::cleanup);
     connect(m_instanceManager, &ApplicationInstanceManager::messageReceived, this, &Application::processMessage);
 #if defined(Q_OS_WIN) && !defined(DISABLE_GUI)
     connect(this, &QGuiApplication::commitDataRequest, this, &Application::shutdownCleanup, Qt::DirectConnection);
 #endif
 
-    if (isFileLoggerEnabled())
+    LogMsg(tr("qBittorrent %1 started", "qBittorrent v3.2.0alpha started").arg(QStringLiteral(QBT_VERSION)));
-        m_fileLogger = new FileLogger(fileLoggerPath(), isFileLoggerBackup(), fileLoggerMaxSize(), isFileLoggerDeleteOld(), fileLoggerAge(), static_cast<FileLogger::FileLogAgeType>(fileLoggerAgeType()));
-
-    Logger::instance()->addMessage(tr("qBittorrent %1 started", "qBittorrent v3.2.0alpha started").arg(QStringLiteral(QBT_VERSION)));
     if (portableModeEnabled)
     {
-        Logger::instance()->addMessage(tr("Running in portable mode. Auto detected profile folder at: %1").arg(profileDir.toString()));
+        LogMsg(tr("Running in portable mode. Auto detected profile folder at: %1").arg(profileDir.toString()));
         if (m_commandLineArgs.relativeFastresumePaths)
-            Logger::instance()->addMessage(tr("Redundant command line flag detected: \"%1\". Portable mode implies relative fastresume.").arg(u"--relative-fastresume"_qs), Log::WARNING); // to avoid translating the `--relative-fastresume` string
+            LogMsg(tr("Redundant command line flag detected: \"%1\". Portable mode implies relative fastresume.").arg(u"--relative-fastresume"_qs), Log::WARNING); // to avoid translating the `--relative-fastresume` string
     }
     else
     {
-        Logger::instance()->addMessage(tr("Using config directory: %1").arg(Profile::instance()->location(SpecialFolder::Config).toString()));
+        LogMsg(tr("Using config directory: %1").arg(Profile::instance()->location(SpecialFolder::Config).toString()));
     }
+
+    if (isFileLoggerEnabled())
+        m_fileLogger = new FileLogger(fileLoggerPath(), isFileLoggerBackup(), fileLoggerMaxSize(), isFileLoggerDeleteOld(), fileLoggerAge(), static_cast<FileLogger::FileLogAgeType>(fileLoggerAgeType()));
+
+    if (m_commandLineArgs.webUiPort > 0) // it will be -1 when user did not set any value
+        Preferences::instance()->setWebUiPort(m_commandLineArgs.webUiPort);
 }
 
 Application::~Application()