DolphinWX: Split cheat window components into their own source files
CheatsWindow: Remove unnecessary wxPanel in the wxDialog

We can simply size the controls within the dialog directly.
DolphinWX: Reimplement cheat listbox updating, but without a global

Just use event handling.
CheatsWindow: unfriend CreateCodeDialog.

This is no longer needed.
Merge pull request #1334 from lioncash/cheats

Break Cheat Manager components out into their own source files.