Mark Unavailable Footprints in PCB Library Table

In the schematic window, when I go to "assign components footprints", it open an ugly error dialog with all footprints libraries that are unavailable (most of them deprecated from github)

there is no actions possible at that moment. Only accept the error.

So, in the footprint libraries dialog, I suggest that it would be a good idea if we can check if they are still available, and mark in red what is missing, so, the user can take some action (for example, find a new library and then remove the deprecated one)