Extend datasets' and files' property from search API endpoint

[ChengShi-1]

Overview of the Feature Request
For the SPA, in order to display the lock icon, and tags/categories information for items in the collection page, we should add some extra properties to each file item from search api once type=file.

• restricted: boolean
• canDownloadFile: boolean ( from file user permission)
• categories: array of string "categories" would be similar to what it is in metadata api, for example, {"label":"blob","description":"","restricted":true,"categories":["Data","Documentation"],"id":6}

For tabular files, there are some properties needed additionally.

• tabularTags: array of string for example,{"tabularTags" : ["Event", "Genomics", "Geospatial"]}
• variables: number/int shows how many variables we have for the tabular file
• observations: number/int shows how many observations for the tabular file

Also, for dataset search api type=dataset, because datasets' thumbnail should be displayed, an extra property is needed.

• thumbnail: string

What kind of user is the feature intended for?
(Example users roles: API User, Curator, Depositor, Guest, Superuser, Sysadmin)
API User

What inspired the request?
Q4 roadmap, Q4.2

What existing behavior do you want changed?
None

Any brand new behavior do you want to add to Dataverse?
Add extra properties

Any open or closed issues related to this feature request?
IQSS/dataverse-client-javascript#221
IQSS/dataverse-frontend#547

[stevenwinship]

Bumping the size to 30

[stevenwinship]

RE:
Also, for dataset search api type=dataset, because datasets' thumbnail should be displayed, an extra property is needed. thumbnail: string

The thumbnail url is already included in the search result for datasets
"image_url": "http://localhost:8080/api/datasets/3/logo",