Add a entity_slug.field_type_categories.yml file and amend categories

Andy Broomfieldrequested to merge
issue/entity_slug-3612552:3612552-missing-entityslug.fieldtypecategories.yml-prevents into 2.x

Fixes issue with adding a new field in the UI by adding missing field_type_categories and fixing the category definition in the slug field types.

Closes #3612552

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