git grep 'def copy' reveals a number of classes that define ad-hoc copy methods but not __copy__ methods. Hence, they do not implement the copy protocol https://docs.python.org/3/library/copy.html, so copy.copy will resort to pickling/unpickling for making a copy.

For the same in sage.tensor, sage.manifolds, see #32476 instead.

For classes whose instances are immutable, see #13811 instead.

CC: @tscrim @mjungmath @nbruin @kwankyu

Component: refactoring

Issue created by migration from https://trac.sagemath.org/ticket/32453