Add a CodeHook class for mid-function hooking

[alexrp]

• Such a hook should receive a pointer to a machine context containing all register values from the target function at the point the hook is called.
• The hook should be able to modify the context before returning and have those modifications flow to the remainder of the target function.
• The user should be able to specify which registers (GPR, XMM/YMM/ZMM, ...) are captured/flowed to reduce the performance impact.
• The hook should use the hook gate infrastructure.

I think all of this should be technically feasible. Probably...