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/tests/core/memory/memory.cpp

@@ -5,6 +5,7 @@
 #include <catch2/catch.hpp>
 #include "core/hle/kernel/memory.h"
 #include "core/hle/kernel/process.h"
+#include "core/hle/shared_page.h"
 #include "core/memory.h"
 
 TEST_CASE("Memory::IsValidVirtualAddress", "[core][memory]") {