Enhancement: re-implement StructureUtil

[cyn0x8]

Please check for duplicates or similar issues before creating this issue.

What is your suggestion, and why should it be implemented?

StructureUtil was removed in the latest release, leaving no easy way to dynamically merge/deep-merge structures (iirc Reflect is blacklisted in hxc)

i was using it for backwards-compatible save data for a mod im working on... re-implementing this class would be extremely helpful so i dont have to null check a ton of variables lol

or, if anyone knows an alternative, please reply with it !!