Add option to limit number of autosaves

Per title, add a dropdown or number input to set exact number of autosaves to keep.

You can set the interval, but you can't limit how many total saves are kept. Short intervals are good for ensuring you don't lose much progress if game crashes or letting you "undo" serious errors. But most players probably don't need more than a few saves.

The save games are not insignificant size and eat disk space over time, which also can require long Steam cloud syncs. You can only delete them manually one at a time in the game interface, and you can't mass delete from Windows OS because the cloud will just recreate them.