(EAI-230): Search endpoint + service

[mongodben]

Jira: https://jira.mongodb.org/browse/EAI-230

Changes

• [ ] GET /search endpoint
• [x] SearchFunc type
• [ ] preprocessedSearch implementation of SearchFunc
• [ ] use a SearchFunc in our implementation, so we can use it in qualitative tests
• [ ] Document endpoint
  • [ ] Add new /server/search page
  • [ ] Update OpenAPI spec

Notes