When allowed paragraphs types selection is set to Exclude new (and so unselected) paragraphs are incorrectly excluded

Problem/Motivation

When "Which Paragraph types should be allowed?" is set to "Exclude the selected below" people will expect that newly created paragraphs will be automatically included. This is not the case, but if somebody re-visits the field settings configuration form it looks correct so instead of saving that form (the workaround) they are likely to keep looking for the source of the problem elsewhere.

Steps to reproduce

1. Add a paragraphs field to a content type, set to exclude the selected.
2. Create a new paragraph type.
3. Create content of the type with that paragraphs field.

Problem: You cannot add a paragraph of the new paragraph type you just created.

Workaround

Re-save Field Paragraphs so all of the paragraph types created since last save show.

Proposed resolution

If feasible, check for all paragraph reference fields with the "Exclude the selected below" setting and programmatically re-save them when a new paragraph type is created. Or alternatively and probably even better if feasible, actually save the excluded types in the configuration and when using this configuration save

If a fix is not feasible, adding a clear warning in the field configuration and in a message when a new paragraph type is added would mitigate this a lot.

Remaining tasks

User interface changes

API changes

Data model changes