Huge thanks to @Szybet for writing at least 95% of the code in this commit

Apparently log() makes the device hang forever on the "Sync in progress" screen. So no option but to remove those calls ...

Don't update it if it isn't necessary.

Otherwise, the screen would flash everytime, regardless of the setting
set by the user. I'm keeping the code
there in case I or someone else find a fix.

Gutenberg-related services (e.g., 'Online library') will now show an error message if they can't connect to the Internet and refuse to launch.