Warn when the canvas size is too small to display the level's content

[ClementSparrow]

Currently, it just displays a black screen. And it has more chances to happen with bigger sprite_sizes and bigger levels.

It would be nice to have a message screen showing the minimal canvas size, and how many pixels are missing. Ideally, we should compute the minimal canvas size for the whole game instead of playing normally until a level gets too big and does not fit in the screen.

It would also be nice, during an export, to write in the console the minimal canvas size so that the value can be provided to host sites like itch.io. Maybe also compute a recommended canvas size that will provide good magnification for all levels (i.e., small margins). And make the console message clickable so that clicking it will set the canvas size to the value in the message.