Add test matcher support for FHIRPath expressions that evaluate to integer.
Add test matcher support for FHIRPath expressions that evaluate to integer.

This will provide better error messages and also prevent the test from crashing when the result is not an integer.

PiperOrigin-RevId: 309808639

google/fhir,google/fhir,google/fhir,google/fhir,google/fhir,google/fhir