See https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-simple-query-string-query.html#simple-query-string-syntax

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# Description

This PR adapts the search engine to support filters based on query
strings applied to fields. This PR only works at the search engine level
and the search endpoints are unaffected.

**Type of change**

(Please delete options that are not relevant. Remember to title the PR
according to the type of change)

- [ ] New feature (non-breaking change which adds functionality)
- [ ] Refactor (change restructuring the codebase without changing
functionality)
- [X] Improvement (change adding some improvement to an existing
functionality)

**How Has This Been Tested**

(Please describe the tests that you ran to verify your changes. And
ideally, reference `tests`)

- [ ] Test A
- [ ] Test B

**Checklist**

- [ ] I added relevant documentation
- [ ] I followed the style guidelines of this project
- [ ] I did a self-review of my code
- [ ] I made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I filled out [the contributor form](https://tally.so/r/n9XrxK)
(see text above)
- [ ] I have added relevant notes to the `CHANGELOG.md` file (See
https://keepachangelog.com/)

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>