Support for loading A Hat in Time packages

[Un-Drew]

Added a custom build for A Hat in Time packages, that gets applied on versions 877-893, licensee version 5. This is to add support for:

• New Class Specifiers: AlwaysLoaded and IterationOptimized.
• New Variable Specifiers: Serialize and Bitwise.
• New Function Specifiers: EditorOnly , Multicast , NoOwnerReplication and Optional (for optional interface functions).
• A property they added in UClass in version 878 that keeps track of the optional interface functions that weren't used. This offsets everything starting from DontSortCategories , so this change is needed to keep those classes readable.

I think this should cover everything they added - hopefully I didn't miss anything. :P

[EliotVU]

Awesome! This what I like to see, 👍🏻