Changes

• Fix 'Test Rumble' functionality in RMG-Input not checking for rumble support since v0.8.1
• Fix exit confirmation checkbox saving the setting when rejecting the dialog
• Remove discord rich presence support
• Remove mupen64plus-input-gca
• Remove fallback to libfmt when 'std::format' isn't supported by the compiler
• Introduce RMG-Input-GCA
• Update mupen64plus-core, GLideN64 and SDL_GameControllerDB