Add helper to modify spi raw file, to make experimenting with it easier.
```sh
$ ./littlefs-do --help
Usage: ./littlefs-do <command> [options]
Commands:
-h, --help show this help message for the selected command and exit
-v, --verbose print status messages to the console
stat show information of specified file or directory
ls list available files in 'spiNorFlash.raw' file
mkdir create directory
rmdir remove directory
rm remove directory or file
cp copy files into or out of flash file
settings list settings from 'settings.h'
```
In the process restructure the CMake file for less duplicate
includes/defines for both executables (`infinisim` and `littlefs-do`).
Upload the `littlefs-do` binary built by the CI additionally to the `infinisim` binary.
Use the updated upload-artifact@v3 template to do that.
