IOS: Add NandUtils

This keeps the ES specific NAND code in a single place and makes it
reusable. Eventually, other ES specific code will be moved to it.

Source/Core/DiscIO/NANDContentLoader.h

@@ -23,6 +23,7 @@ namespace DiscIO
 {
 enum class Region;
 
+// TODO: move some of these to Core/IOS/ES.
 bool AddTicket(const IOS::ES::TicketReader& signed_ticket);
 IOS::ES::TicketReader FindSignedTicket(u64 title_id);