Finished basic task switching mechansim

PCB is local to a process's address space.
Context switches are written in assembly.
Moved x86 headers to include/x86

src/x86/apic.c

@@ -1,7 +1,7 @@
 #include "mmgr.h"
 #include "allocator.h"
-#include "apic.h"
-#include "msr.h"
+#include "x86/apic.h"
+#include "x86/msr.h"
 #include "stdio.h"
 #include <stddef.h>
 
@@ -38,6 +38,7 @@ void apic_enable(struct page_stact_t *page_stack)
     map_page(page_stack, apic_registers, msr.apic_base << 12, PAGE_RW);
     printf("MSR_APIC_BASE: %016x\n", *((uint32_t*)&msr));
     apic_registers->spurious_iv.value = apic_registers->spurious_iv.value | 0x1FF;
+    apic_registers->destination_format.value = 0xFFFFFFFF;
 }
 
 void apic_eoi()