This pr allows for configuring the framerate target and adds support for two other framerate targets, a "fastforward" and "slowmo" target which can be enabled via either a toggle or holding a button.
this allows for supporting a more accurate framerate target and allows for users to slow down the speed of gameplay if they so desire
* Make `EmuInstance::cheatFile` use a `unique_ptr`
- Fixes a memory leak, as the cheat file wasn't cleaned up in the destructor
* Split `AREngine` and `ARCodeFile` apart
- Suitable for frontends that have their own way of storing cheats
- Store the cheats in `AREngine` in a `std::vector`
- Apparently cheats are _supposed_ to be executed each frame; I didn't understand this until recently
non-exhaustive (but exhausting) list of changes:
* base laid for multiple window support, but will likely require more work to work correctly
* encapsulation of frontend state for proper multi-instance support
* (JIT still needs a fix for the NDS::Current workaround but we can get there later)
* new, more flexible configuration system
