Make the runtime configuration dialog non-modal. Fixes #5490

Major refactoring of the runtime code, Specifically:
  - Move the bulk of the core code from main() into a new Runtime class.
  - Break up the mass of code that was main() into a number of relatively simple functions.
  - Make the Configuration dialog synchronous so the Log dialog can be properly viewed.
  - Enable/disable menu options at the right time.
  - Remove support for Qt < 5.0.
  - Remove the application name constant and hardcode the name to simplify the code.
  - Improve log messages.
  - Replace the sdbm hashing with Qt's MD5 hashing.

runtime/Runtime.h

@@ -0,0 +1,65 @@
+//////////////////////////////////////////////////////////////////////////
+//
+// pgAdmin 4 - PostgreSQL Tools
+//
+// Copyright (C) 2013 - 2020, The pgAdmin Development Team
+// This software is released under the PostgreSQL Licence
+//
+// Runtime.h - Core of the runtime
+//
+//////////////////////////////////////////////////////////////////////////
+
+#ifndef RUNTIME_H
+#define RUNTIME_H
+
+// Include the Python header here as it needs to appear before any QT
+// headers anywhere in the app.
+#ifdef __MINGW32__
+#include <cmath>
+#endif
+#include <Python.h>
+
+#include "TrayIcon.h"
+#include "MenuActions.h"
+#include "FloatingWindow.h"
+
+// QT headers
+#include <QtWidgets>
+
+class Server;
+
+class Runtime: public QObject
+{
+    Q_OBJECT
+public:
+    Runtime();
+
+    bool alreadyRunning();
+    bool go(int argc, char *argv[]);
+    void delay(int milliseconds);
+    bool shutdownServer(QUrl url);
+
+private:
+    QSettings m_settings;
+    QSharedMemory *m_shmem;
+    bool m_configDone;
+
+    void setupStyling(QApplication *app);
+    void configureProxy();
+    QSplashScreen *displaySplash(QApplication *app);
+    quint16 getPort();
+    TrayIcon *createTrayIcon(QSplashScreen *splash, MenuActions *menuActions);
+    FloatingWindow *createFloatingWindow(QSplashScreen *splash, MenuActions *menuActions);
+    Server *startServerLoop(QSplashScreen *splash, FloatingWindow *floatingWindow, TrayIcon *trayIcon, int port, QString key);
+    Server *startServer(QSplashScreen *splash, int port, QString key);
+    void checkServer(QSplashScreen *splash, QString url);
+    void createAddressFile(QString url);
+    void openBrowserTab(QString url);
+    QString serverRequest(QUrl url, QString path);
+    bool pingServer(QUrl url);
+
+private slots:
+    void onConfigDone(bool accepted);
+};
+
+#endif // RUNTIME_H