hypervisor: x86: Add an InstructionHandler interface

And an InstructionMap helper structure to map x86 mnemonic codes
to instruction handlers.

Any instruction emulation implementation should then boil down with
implementing InstructionHandler for any supported mnemonic.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

hypervisor/src/arch/x86/emulator/mod.rs

@@ -10,6 +10,8 @@ use crate::arch::emulator::PlatformError;
 use crate::x86_64::{SegmentRegister, SpecialRegisters, StandardRegisters};
 use iced_x86::*;
 
+mod instructions;
+
 /// CpuStateManager manages an x86 CPU state.
 ///
 /// Instruction emulation handlers get a mutable reference to