Add private DataDoc to search functionality

[ldziko]

Currently, all private DataDocs are not indexed on Elasticsearch for simplification of logic. Since most of the DataDocs will be private by default with FGAC, it is essential to make them searchable from Elasticsearch. The new Elasticsearch table for DataDocs should include 2 more fields: public and readable_user_ids. The second field readable_user_ids should include every user who can access this private DataDoc.