[Improvement] Rewrite Player class to use Pawns

[Hri7566]

Player class was used in the original sandbox mode, but is deprecated now.

This one will probably take a lot longer.

[Nebual]

I believe SnakeSVx of Spacebuild is looking at replacing our Player class, likely with a better collision/movement model including supporting dynamic gravity, so if anyone's looking to collaborate they may want to reach out in the Spacebuild discord :)