This change makes so that data that exists in MongoDB but isn't defined
in the Payload config won't be included to `payload.find` /
`payload.db.find` calls. Now we strip all the additional keys.
Consider you have a field named `secretField` that's also `hidden: true`
(or `read: () => false`) that contains some sensitive data. Then you
removed this field from the database and as for now with the MongoDB
adapter this field will be included to the Local API / REST API results
without any consideration, as Payload doesn't know about it anymore.
This also fixes https://github.com/payloadcms/payload/issues/11542 if
you removed / renamed a relationship field from the schema, Payload
won't sanitize ObjectIDs back to strings anymore.
Ideally you should create a migration script that completely removes the
deleted field from the database with `$unset`, but people rarely do
this.
If you still need to keep those fields to the result, this PR allows you
to do this with the new `allowAdditionalKeys: true` flag.