tensor/full should not create a copy

[tgkolda]

The tensor.full function is just there to match with "full" function for other tensors. It should ideally just return the tensor itself and not a copy.

[ntjohnson1]

Confirmed this diverges from MATLAB tensortoolbox (oversight on my part) https://gitlab.com/tensors/tensor_toolbox/-/blob/dev/@tensor/full.m?ref_type=heads

A quick check of setting the new tensor to not copy the underlying data passed all of our tests. So we can probably just return self and update the doc string.