Utility for copying that check that everything is supported

[blegat]

I'm always a bit worried when I implement a custom copy_to that I might be only looking at the part of the model that I support and ignoring things for which I should throw an error.
We could have a generic function like the one implemented in osqp/OSQP.jl#128 that could just be called by solver wrappers.
It would be similar to a dry run of copy_to that does not actually copy anything.
It could be something like throw_if_copy_to_not_supported(dest, src).

[odow]

We have a test. OSQP was just skipping it: https://github.com/osqp/OSQP.jl/pull/128/files#r1984127888

[odow]

I don't think this needs to be a new utility. I'm in favor of closing this issue.