Implemented solution

openapi spec update to add numOfCitation
added a new column (right most part of the table as in the video shown) - @filippomc - let me know if positioning needs to change. Also the header of the column is - "Number of Citation".
allow sorting (only - no filtering - since filtering for this would be like - greater than, smaller than - as this is a number - which we don't have as of now).
update mappers for FE and BE allow citation for sorting

How to test this PR

No specific Unit test added. This only extends to also include - "citation" for FILTERABLE_AND_SORTABLE_FIELDS Please check the video : )

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