Add system time configuration (#4043)

* Add setting to switch between a fixed start time and the system time

Add clock settings to SDL

Make clock configureable in qt

Add a SharedPage handler class

Init shared_page_handler for tests

src/core/core.cpp

@@ -174,6 +174,7 @@ System::ResultStatus System::Init(EmuWindow* emu_window, u32 system_mode) {
 
     telemetry_session = std::make_unique<Core::TelemetrySession>();
     service_manager = std::make_shared<Service::SM::ServiceManager>();
+    shared_page_handler = std::make_shared<SharedPage::Handler>();
 
     HW::Init();
     Kernel::Init(system_mode);