crypto: add Hash.prototype.copy() method

Make it possible to clone the internal state of a Hash object
into a new Hash object, i.e., to fork the state of the object.

Fixes: https://github.com/nodejs/node/issues/29903

PR-URL: https://github.com/nodejs/node/pull/29910


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>