Break Cheat Manager components out into their own source files.

Pretty self explanatory. Done in preparation for eventual RAM watch functionality. For this, the `CheatSearchTab` will be re-purposed into an agnostic `wxPanel` that can be used for both cheats and said RAM watch function.

Doing this also eliminates a dumb global that was used to reload the cheat-list with newly created cheats. This is now done through event propagation.