Initial sandwich solution implementation in SheeKit

SheeImplementation-SheetHostingController.swift

final class SheetHostingController<Item>: UIHostingController<AnyView> where Item : Identifiable {
    var itemId: Item.ID?
    var item: Item
    var onDismiss: (() -> Void)?
    
    init(rootView: AnyView, item: Item) {
        self.itemId = item.id
        self.item = item
        super.init(rootView: rootView)
    }
    
    @available(*, unavailable)
    @MainActor
    @objc
    required dynamic init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}