Function unnest_list_array 

fn unnest_list_array(
    list_array: &dyn ListArrayType,
    length_array: &PrimitiveArray<Int64Type>,
    capacity: usize,
) -> Result<ArrayRef>

Unnest a list array according the target length array.

Consider a list array like this:

[1], [2, 3, 4], null, [5], [],

and the length array is:

[2, 3, 2, 1, 2]

If the length of a certain list is less than the target length, pad with NULLs. So the unnested array will look like this:

[1, null, 2, 3, 4, null, null, 5, null, null]