test: add promises metadata to postmortem test

type_JSPromise__JS_PROMISE_TYPE and
type_JSMessageObject__JS_MESSAGE_OBJECT_TYPE will be used on llnode to
identify Promises in memory and core dumps:
https://github.com/nodejs/llnode/pull/272. Add these to our postmortem
test so we're aware of any changes to this metadata.

PR-URL: https://github.com/nodejs/node/pull/31357


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>