Search: option to show results only if it matches all types

Suggested in 1739460-zen

I'd like search results for job listings with multiple job types to only display if they possess all of the tagged job types. E.G. If a job listing has both HOURLY CONTRACT & FULLY REMOTE job types, when both of these job types are tagged via the front end search, ONLY job listings which possess BOTH job types display in the search results. Currently, the search results pick up all job listings that have either job type tagged. Thank you.

Start by tracing the front-end search handling for multiple job-type filters in the WP-Job-Manager repository. Reproduce the example with HOURLY CONTRACT and FULLY REMOTE selected, then identify the existing search tests or add coverage for the combined filter. Done means results include only listings possessing every selected job type.

Written by the indexing model from the issue text.