[frontend] refactor: extract common firmware & key functions (#38)

Extracts some firmware version/verification functions into
`frontend_common` to reduce duplicate code, especially for the new QML
frontend.

Additionally adds a check for games that are known to require firmware
(e.g. MK8DX) and warns the user if they don't have firmware installed
and attempt to run the game.

Firmware installation is to be in a separate PR.

Signed-off-by: crueter <crueter@eden-emu.dev>
Co-authored-by: Aleksandr Popovich <popovich@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/38

src/frontend_common/CMakeLists.txt

@@ -5,6 +5,8 @@ add_library(frontend_common STATIC
     config.cpp
     config.h
     content_manager.h
+    firmware_manager.h
+    firmware_manager.cpp
 )
 
 create_target_directory_groups(frontend_common)