tweak(gamestate/server): Parse CPickupCreationDataNode

[tens0rfl0w]

Goal of this PR

Allowing to get the entity model of a pickup object on the server-side.

How is this PR achieving the goal

Parse CPickupCreationDataNode partially and return the custom model hash (if set) on GET_ENTITY_MODEL.

This PR applies to the following area(s)

FiveM, Server

Successfully tested on

Game builds: 2060, 2699, 3258

Platforms: Windows (Client)

Checklist

• Code compiles and has been tested successfully.
• Code explains itself well and/or is documented.
• My commit message explains what the changes do and what they are for.
• No extra compilation warnings are added by these changes.

Fixes issues

resolves #2924

[spacevx]

With this data node you could create a server setter no?

[tens0rfl0w]

Without verifying: Yeah that should work, though this node has a lot more serialization stuff going on, so completing this isn't super easy.

[william-des]

This bug made it possible to easily block the creation of pickups by canceling any entity with a model hash of 0 in the entityCreating event.
I don't think there is any other way to to distinguish between pickups and regular objects server side, and maybe a native can be created for that ?

[tens0rfl0w]

The modelhash will still be 0 if no custom model is supplied, as the game will then just use the metadata of the pickup type to determine which model to render. This is a limitation that will be hard to overcome as we have no metadata on the server (yet). I can have a look if we can implement something like GET_PICKUP_HASH on the server-side to check what type of pickup this object is.

[iridium-cfx]

May be worth adding a comment that this isn't all of the node data.