Please add a function or hook to distinguish between shutting down and changing the map

[abmk4ufls]

Details

Please add a function or hook that distinguishes between shutting down and changing the map, and add a "before" and "after" so we can use them for specific purposes. This will be useful when you have something and want to check its status before switching to a different map, or after shutting down the server and then starting it up later. Therefore, we need a function that distinguishes between shutting down and changing the map.

[robotboy655]

Duplicate of https://github.com/Facepunch/garrysmod-requests/issues/1221