kern: Implement most of memory init (all cores hit main, but still more to do)

libraries/libmesosphere/include/mesosphere/init/kern_init_arguments_select.hpp

@@ -25,5 +25,7 @@
 namespace ams::kern::init {
 
     KPhysicalAddress GetInitArgumentsAddress(s32 core_id);
+    void SetInitArguments(s32 core_id, KPhysicalAddress address, uintptr_t arg);
+    void StoreInitArguments();
 
 }