Kernel: Rewrite all kernel mutexes

Now SpinLock is actually just a spin lock and I added a Mutex that
does the same as the old "SpinLock". This is in preparation for
starting to support smp and making the kernel smp safe. This commit
also removes obsolete PageTableScope and CriticalScope which should
now be used by alternative APIs.

kernel/arch/x86_64/PageTable.cpp

@@ -1,7 +1,7 @@
 #include <kernel/Arch.h>
 #include <kernel/CPUID.h>
 #include <kernel/InterruptController.h>
-#include <kernel/LockGuard.h>
+#include <kernel/Lock/LockGuard.h>
 #include <kernel/Memory/kmalloc.h>
 #include <kernel/Memory/PageTable.h>
 
@@ -22,6 +22,8 @@ namespace Kernel
 	static bool s_has_nxe = false;
 	static bool s_has_pge = false;
 
+	SpinLock PageTable::s_fast_page_lock;
+
 	// PML4 entry for kernel memory
 	static paddr_t s_global_pml4e = 0;