Move ResourceResponse out of rest module

Problem/Motivation

Drupal\rest\ResourceResponse is very useful for anyone doing JSON responses, because it allows cacheability.

However, it introduces a dependency on rest module.

Steps to reproduce

Proposed resolution

Not sure.

First attempts here were to move the class into Core-core (ie Drupal\Core\*).

However, ResourceResponse relies on ResourceResponseSubscriber to create the output, and that has a dependency on serialization module, so it can't do into Core-core.

Could ResourceResponse and ResourceResponseSubscriber be moved into serialization, to provide a generic way of returning data responses?

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet