Function pxs_listset 

#[unsafe(no_mangle)]
pub extern "C" fn pxs_listset(
    list: *mut pxs_Var,
    index: i32,
    item: *mut pxs_Var,
) -> bool

Set a item at a specific index in a pxs_VarList.

Expects a pointer to pxs_VarList, a index of i32, and a pxs_Var. Supports negative indexes jsut like in Python.

Will take ownership of the pxs_Var.

This will return a boolean for success = true, or failure = false.