Add "Doctoral Culminating Experience" work type

[ajkiessl]

This is a scholarly work. There's a handful of places this will need to be added:

• The Work model method that stores the names of allowed scholarly works
• The openapi configuration
• The thumbnail component to determine the default icon
• Datacite WorkVersion RESOURCE_TYPES

[ajkiessl]

There may be more places, but an initial search gives me these ☝️