Use sympy functions and generalise `make_matrix_or_array`

[alexvong243f]

This PR is mostly about changing embedded python code to use sympy functions, similar to #1230.

We also fix an (im)mutability bug exposed by this change. Finally, we generalise make_matrix_or_array to accept an iterable of iterables.

[cbm755]

We also fix an (im)mutability bug exposed by this change.

Does this need a new BIST?

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LGTM, please merge when you're ready

[alexvong243f]

Currently, the test in @sym/subsasgn

%!test
%! % Disassemble matrix
%! a = sym([1 2; 3 4; 5 6]);
%! b = sym([3 5 2 4 6]);
%! a(1) = [];
%! assert (isequal (a, b));

fails if we revert 321ee1709f011ea568a243d5f8722fa6e3a14db9 so it should be fine (?)