Tests: expand search coverage for searchtools.js

[jayaddison]

Feature or Bugfix

• Feature (tests)

Purpose

• Improve the test coverage of the searchtools.js search index/querying functionality, to aid maintenance and development.

Detail

• [ ] Object-name matching.
  • [ ] Fully-qualified path.
  • [ ] Local-lexical-scope names.
  • [ ] Priorities.
• [ ] Document title matching.
• [x] Exact-matching.
• [x] Multi-word document term matching.
• [ ] Partial document term matching.
• [ ] Single-document and multi-document terms in the index (when a term only exists within a single document, it appears as {term: 1} in the index, instead of within an Array such as {term: [0, 1, 2, ...]} in the multi-document case.

Relates

• Follows-up / inspired-by #12029.