Pass permutation array to transform dof ordering

[garth-wells]

At the moment, Basix generates elements with a fixed (reference) ordering of dofs on a cell. This reference ordering is not suitable for all algorithms/kernels.

It would be helpful to pass a permutation array to Basix when creating an element to change the ordering. A reason for doing this at Basix level would be to avoid repeated applied permutations in other libraries.

[garth-wells]

@mscroggs, @IgorBaratta can this be closed now?