Update rcheevos, and with that add in the new DSi console ID
Experimentally revamp the build system, I'm looking into cmake here and it seems to do a great job. The builds committed here were built with clang-cl 15.0.1 and clang 15.0.7 (for Windows and Linux respectively). gcc/clang with msys2 still works fine. gcc on Linux should still work fine. MSVC (cl) itself even works (although as a note, it doesn't work with lto (/GL) due to the force everything exported flag I set). The old Makefile is still kept for future reference.