Option for modders to set their items as unshared by default, and making them shared through a "whitelist" config option

[TheMysticSword]

Is your feature request related to a problem? Please describe.
Certain items in my mod, Mystic's Items, are very unbalanced when shared with everyone on the team.
For example, the Faulty Spotter that marks 1 random enemy and lets everyone deal 100% crits against it, becomes way too powerful. The item is already "shared" in a sense that the mark lets everyone deal crits against that enemy.
Another example is the Treasure Map item that creates a charge zone with a charge time that is reduced for each stack of the item on the player's team - with ShareSuite, if one person picks it up, it gets shared with everyone, reducing the charge time, which is not intended.

Describe the solution you'd like
Modders should be able to call an API function in ShareSuite (for example, ShareSuite.ModdedItemBlacklist.AddItemToBlacklist(string itemName)) in their code, making the item not shared by default.
The ShareSuite config should have a ModdedItemWhitelist entry. If a user puts an item name in there, it won't get blacklisted by AddItemToBlacklist.

[FunkFrog]

I plan on getting, if nothing else, this implemented over my break.