Allow opt-out of automatic meta.drupal_internal__target_id on entity relationships

Problem/Motivation

#3036593: Add 'drupal_internal__target_id' to JSON:API representation of entity reference fields, because that can't be retrieved from the target resource for target entity types without corresponding resources added a meta.drupal_internal__target_id value on the relationship identifier for entity reference fields; this is super helpful to client-side implementations to filter by Drupal IDs, rather than UUID.

There are some circumstances (user IDs, for instance) where I would like to hide Drupal's internals, entirely. Serial fields in particular can leak information relating to the site's total user count, or the relative age of a user, or whatever, from the ID.

This isn't a huge issue, and enumeration of Drupal users (and other entities) by ID is not considered a security risk per se, but this value's automatic inclusion makes it harder to build a site that is API-forward in using UUIDs everywhere.

Because json:api module exposes a very limited PHP API, this is difficult to adjust in contrib or custom code.

It might be interesting to couple this with an opt-out of all the drupal_internal__* meta members, but this may be too edge a use case to make sense in core. The issue is mostly that this is pretty difficult to opt-out of without hacking core, since there is no real hookpoint to adjust this.

Proposed resolution

Allow the meta member on the resource linkage to omit this Drupalism, by adding a container parameter.

Remaining tasks

Maintainer review... tests maybe?

User interface changes

None.

API changes

New container parameter and change to an internal constructor signature, but this is in the internal API.

Data model changes

None

Release notes snippet

TBD