Implement a way to prevent players from downloading custom models after connection

Is your feature request related to a problem? Please describe.
Not exactly a problem, but as a few people suggested before, preventing users to download custom models right after connecting can help with bunch of stuff, like authorizing them first before forcing them to download files

Describe the solution you'd like
A function that disables sending custom model info RPC when a player is connected, only to be sent later, whenever the developers want it to be. This way they'll have control over it and they can do whatever that needs to be done before downloading starts, for example authorizations and etc

Additional context
Also adding a method to trigger players to download leftover models or whatever else they need to have, by sending model info RPC and then switching virtual worlds (to a new one and then reverting it)

Start by tracing the custom model info RPC sent when a player connects and the virtual-world switching entry points. Define how developers defer that RPC and later trigger leftover model downloads, then verify that connection no longer starts downloads before authorization and that the explicit trigger does.