[BUG] Including `search_term` in `/search` ignores numerous search terms

[philip-davis]

The handling of search_term is confusing. If a user provides a search_term, we skip trying to match on dataset_name, dataset_title, owner_org, and dataset_description, which seems undesirable:

scidx-api/api/services/datasource_services/search_datasource.py

Line 39 in aeb10a3

else: