Modify constraint to allow new ignored entities

Problem/Motivation

Following #3101671: Add mechanism to have workspaces skip processing entity types, we have the notion of ignored entity types.

In #3259701: Override entity reference validation constraint of core workspaces, this module introduced a constraint validator that softened core's version, allowing us to create "internal" entities on an entity reference field. That issue mentioned a future state in which the notion of "ignored" entities was also considered. Now we can make that future a reality.

Steps to reproduce

Install WSE and try to add a Paragraph entity inside a Workspace. We get a message "Paragraphs can only be created within the default workspace."

Proposed resolution

Add another check to the already long list of conditions in the WseEntityReferenceSupportedNewEntitiesConstraintValidator

Remaining tasks

User interface changes

API changes

Data model changes