Split Screen Mode for more then 1 controller

[mingai-nexucore]

Add split screen. (the game does have split screen but it says to press START, but if i do it. It doesnt work, it would be really cool if this thing had split screen. I would play with my siblings)

[Cath0deGayTube]

Split screen was kind of working earlier (this was on the main source leak I tested it, not this repo), it's just that player 2 would have a ghost playermodel following them that would block their view and player 2 pausing would softlock them. I wonder what broke it even more

[Kat-09]

This would be great to see

[BluedragonMask]

@codeHusky Duplicate issues were listed in this discussion, should close those.

[BluedragonMask]

Also #305

[mschiller890]

I got it working by bypassing the IsLocalGame() requirement so controllers can join without a signed-in profile.

To remove the ghost player model, I detect AddPlayerPackets that belong to local controllers by matching the packet XUID with the IQNet-derived XUID and skip creating a RemotePlayer for them.