AK: Rename the common integer typedefs to make it obvious what they are.

These types can be picked up by including <AK/Types.h>:

* u8, u16, u32, u64 (unsigned)
* i8, i16, i32, i64 (signed)

Kernel/IRQHandler.cpp

@@ -2,7 +2,7 @@
 #include "PIC.h"
 #include <Kernel/Arch/i386/CPU.h>
 
-IRQHandler::IRQHandler(byte irq)
+IRQHandler::IRQHandler(u8 irq)
     : m_irq_number(irq)
 {
     register_irq_handler(m_irq_number, *this);