Curios pre-calculate available slots

You could notice that sometimes Curios would drop items from extra slots when you log in or die with keep inventory, that happened due to some edge cases where Curios assumed you don't have any additional slots at all.

This mod is a temporary solution to this issue, it forces Curios to pre-calculate amount of additional slots that makes all further calculations correct.

Issue with Curios - https://github.com/TheIllusiveC4/Curios/issues/575