Unreal: Expose UObject creation and address

[PARTYMANX]

(This is built off of #110, as I needed both sets of functionality for my own testing, sorry for any confusion!)

Adds new and get_address functions to the UObject struct.

I refactored the THPS 1+2 and 3+4 splitters to use UObject fields wherever possible to make them a bit more generic (in case another game or significant updates come out), which required the UObject struct to be able to be created for arbitrary addresses. I have an example of its usage here: https://github.com/PARTYMANX/thps-autosplitter/blob/unreal-stage2/src/alcatraz_utils/mod.rs#L220

[Jujstme]

Why would you need to make a new UObject instead of reading it directly via process.read::<UObject>()?

[PARTYMANX]

I don't remember for sure, but I'm pretty sure I had tried that but ran into issues because UObject only contains an Address of a variable size.