Add direct-reference codes to the manifest

[brynrhodes]

The current process for producing a manifest collects only canonical dependencies, it does not collect direct-reference codes. Add direct-reference codes (using the cqf-directReferenceCode extension) to the manifest as part of the release processing.

[brynrhodes]

Measure effective data requirements include direct-reference codes that are referenced by the measure, specified with the cqf-directReferenceCode (in STU5) or cqfm-directReferenceCode (in STU4). When releasing a manifest, the gather does not add direct-reference codes from Measures.

For an example of the Measure content:
https://github.com/cqframework/ecqm-content-qicore-2025/blob/57d88e00255b6d0822aed8e3f3e7dd8a6f546046/input/resources/measure/CMS1056CTClinicalFHIR.json#L11

In addition to what it currently does, the $release operation should gather any direct-reference codes referenced by component measures and add them to the manifest, using the directReferenceCode extension slice on the root of the release manifest:

https://hl7.org/fhir/uv/crmi/StructureDefinition-crmi-manifestlibrary.html

[brynrhodes]

Note that the code should be tolerant of STU4/STU5+, so it should work with cqfm-directReferenceCode and cqf-directReferenceCode in the Measure source, but it should always output cqf-directReferenceCode extensions in the Manifest (because cqfm-directReferenceCode isn't allowed in a CRMIManifest)

[Chris0296]

@brynrhodes Is it safe to assume that STU4 will always have 'cqfm-directReferenceCode' and STU5 will always have 'cqf-directReferenceCode' or are both valid for both versions?