`_text` does not work with R5

[tadgh]

Replication setup:

1. Enable Lucene/ES
2. Enable Fulltext indexing
3. Setup an R5 Persistence module.
4. Create a ServiceRequest with a narrative containing asdf.
5. Attempt:

   GET ServiceRequest?_text=asdf

Result:

{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "processing",
      "diagnostics": "HAPI-1088: Unsupported full-text param type: class ca.uhn.fhir.rest.param.SpecialParam"
    }
  ]
}