test with Vector type instead of Array (Virgil)

FilterWasm-test.v3

def imgProc_gray(width: int, height: int, channels: u8, inputData: Pointer) -> Pointer {
    var imgProc = ImgProc.new(width, height, channels);
    var inputData_size = width * height * channels;
    var internal_data: Vector<byte> = Vector<byte>.new();
    for (i = 0; i < inputData_size; i++) {
        internal_data[i] = (inputData + i).load<byte>();
    }

    return Pointer.atContents(imgProc.grayscale(internal_data));
}

/*
//  This is the error with the Vector version
./build.sh
[FiltersWasm.v3 @ 29:30] TypeError: cannot infer type parameter T of "atContents"
    return Pointer.atContents(imgProc.grayscale(internal_data));
                             ^
[FiltersWasm.v3 @ 29:31] TypeError: call requires type Range<?> and found Vector<byte>
    return Pointer.atContents(imgProc.grayscale(internal_data));
*/