fs.mitm: WIP LayeredFS impl (NOTE: UNUSABLE ATM)

Also greatly refactors libstratosphere, and does a lot of other things.
There is a lot of code in this one.

stratosphere/fs_mitm/source/fsmitm_worker.hpp

@@ -2,9 +2,9 @@
 #include <switch.h>
 #include <stratosphere.hpp>
 
-class FsMitmWorker {
+class FsMitMWorker {
     private:
-        static Result AddWaitableCallback(Handle *handles, size_t num_handles, u64 timeout);
+        static Result AddWaitableCallback(void *arg, Handle *handles, size_t num_handles, u64 timeout);
     public:
         static void Main(void *arg);
         static void AddWaitable(IWaitable *waitable);