v8: use AliasedBuffers for passing heap statistics around

Instead of holding shared pointers to ArrayBuffers, simplify
the code by using AliasedBuffers directly which allows the
binding to own the buffers.

PR-URL: https://github.com/nodejs/node/pull/32929


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>