Simplify Modules management and core components

List of changes:

• Reordered CMakeLists.txt and SkywardHub.pro
• Updated CI script to set expiration time for artifacts
• Updated Module class and subclasses implementation:
  • Function toWidget() is no more needed
  • Context menu creation has been reorganized: It is handled by the Module class code. Subclasses only need to add custom action to the customContextMenuActions variable once in the costructor
• SkywardHubMainWindow has been removed in favor of a simplier class Window that extends QMainWindow and handles widgets creation from xml object and its main child
• ModulesManager has been removed
• SkywardHubCore was treated as a singleton via SkywardHubCoreProxy and gave access to ModulesManager, EventHandler and MessageBroker. Now SkywardHubCoreProxy has been removed and SkywardHubCore made a singleton. Its purpose is now to manage Windows and handle load and save operations from the xml where the profile is saved
• ModulesList, EventHandler and MessageBroker are now a singletons
• EventHandler was used as an interface to provide QT slots for modules. This was unneccessary and removed
• All the modules have been updated to follow all this changes