Add search by only ID (for search by reference)

[projkov]

According to the specification, the responder SHALL support search by resourceType/id and id. In the current implementation only search by resourceType/id.

Add search by id.

The issue was found in the context of working on this issue: #208

Where to check:

1. Encounter -> location
2. Observation -> patient
3. PractitionerRole - organization

[projkov]

For the "patient" search parameters, the US Core Inferno Suite has a specific behavior. It's described in these files. If you want to check them, please check them in the suggested order:

1. au-fhir-core-inferno/lib/au_core_test_kit/generator/search_test_generator.rb

   Line 230 in 814d5e9

   first_search? && search_param_names.include?('patient')

2. au-fhir-core-inferno/lib/au_core_test_kit/generated/v1.0.0-ci-build/bloodpressure/bloodpressure_patient_code_search_test.rb

   Line 50 in 814d5e9

   test_reference_variants: true,

3. au-fhir-core-inferno/lib/au_core_test_kit/search_test.rb

   Line 196 in 814d5e9

   perform_reference_with_type_search(params, resources_returned.count) if test_reference_variants?

4. au-fhir-core-inferno/lib/au_core_test_kit/search_test.rb

   Line 327 in 814d5e9

   def perform_reference_with_type_search(params, resource_count)

As you can see this search parameter suite will make a search request with resourceType/id only when it is the first search. We can remove it or keep it as it is.

This is the theme to discuss with @ir4y on tomorrow's call on 3 December.