Deprecate node_is_page and move into a service

Problem/Motivation

node_is_page is a procedural function, we can move it into a service to make it more extensible.

See 📌 Make node aware of the latest_version route. Needs work

Proposed resolution

Add a new service called NodeTBC (maybe this could be NodeRepository to be used in 📌 Create a new NodeRepository for the code from Drupal\node\NodeStorage Active as well.

Remaining tasks

Agree on naming
Do it

API changes

node_is_page is deprecated
New service to do the same work

Release notes snippet

node_is_page is deprecated, use X instead.