[Patch] Move title management and main frame layout to new class.

[michael2402]

Work for #12925

Create a new MainFrame class to:

• Move the refreshTitle() out of MapView
• Move the window icon code there
• Move maximized check there
• Add a new reference to the main window to MainApplication
• Restructure some hooks to resolve dependencies during startup.
• Main() does not do the work in the constructor any more and uses initialize():

To be done later:

• Clean up Icon code
• Re-enable the test that checks if the window size parameter works (does not work now since we cannot construct the frame in headless mode)