SearchHelper can be simplified using new Globus Search features

[WardLT]

We should re-implement the search helper to make it push more query logic onto Globus Search using its new API features. For example, many of the "exclusion" operations could be implemented via filters instead complex modifications of a single query string.

[WardLT]

For reference, Globus Search docs: https://docs.globus.org/api/search/query/