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
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
