Clean some forward declarations.

Remove unused (wrong copy&paste) includes from rP21778 in JSInterface_ModIo.*, initially hinted at by leper.
Remove a forward declaration in JSInterface_Console.h that should have become an include with rP14496, because CxPrivate must be declared before its reference too.
Remove a forward declaration in JSInterface_Mod.h from rP15677 that should have been the include added in rP20591 which in turn omitted to remove this forward declaration.
Remove a forward declaration in Renderer.h that became unused with rP20019.

Differential Revision: https://code.wildfiregames.com/D1470
Reviewed By: Itms