CORE-4334 Updates for Desktop layouts resizing windows.

Updated CascadeDesktopLayout and CenterDesktopLayout to no longer resize windows in their layoutWindow methods, since this could shrink non-resizable windows to an unusable size.
Updated the DesktopLayout classes to preserve maximized windows in their layoutDesktop methods.
Removed the isMaximized check in the Desktop#layout method.
Added an IPlantWindowInterface#setMaximized method.
Refactored the maximize and restore logic in IplantWindowBase into its new setMaximized method.