Add the HelmComponentDetector and associated tests.

[jpinz]

This pull request introduces a new Helm chart image reference detector, HelmComponentDetector, to the component detection system. The detector is disabled by default and must be explicitly enabled. It scans Helm values files for Docker image references, supporting both direct and structured formats, and is integrated into the detection orchestrator. Documentation and test resources are also added to support and describe this new functionality.

[github-actions]

👋 Hi! It looks like you modified some files in the Detectors folder.
You may need to bump the detector versions if any of the following scenarios apply:

• The detector detects more or fewer components than before
• The detector generates different parent/child graph relationships than before
• The detector generates different devDependencies values than before

If none of the above scenarios apply, feel free to ignore this comment 🙂

[Copilot]

Pull request overview

Adds a new DefaultOff Helm detector to Component Detection that scans Helm values files for Docker image references, wiring it into the orchestrator and documenting/testing the behavior.

Changes:

• Introduces HelmComponentDetector to discover Docker image references in Helm *values*.y{a}ml files co-located with Chart.yaml/Chart.yml.
• Registers the detector in orchestrator DI and adds DetectorClass.Helm.
• Adds unit tests plus verification test resources and documentation for Helm detection.

Show a summary per file

File	Description
test/Microsoft.ComponentDetection.VerificationTests/resources/helm/values.yaml	Adds verification Helm values examples with multiple image reference formats.
test/Microsoft.ComponentDetection.VerificationTests/resources/helm/Chart.yml	Adds a minimal chart metadata file for verification resources.
test/Microsoft.ComponentDetection.Detectors.Tests/HelmComponentDetectorTests.cs	Adds extensive unit coverage for direct/structured image formats, digests, nesting, and chart co-location behavior.
src/Microsoft.ComponentDetection.Orchestrator/Extensions/ServiceCollectionExtensions.cs	Registers HelmComponentDetector with DI so it can be enabled via detector args.
src/Microsoft.ComponentDetection.Detectors/helm/HelmComponentDetector.cs	Implements Helm values YAML parsing and Docker image extraction logic.
src/Microsoft.ComponentDetection.Contracts/DetectorClass.cs	Adds DetectorClass.Helm enum value.
docs/detectors/helm.md	Documents detector requirements, strategy, and limitations.
docs/detectors/README.md	Adds Helm detector entry and status table.

Copilot's findings

• Files reviewed: 8/8 changed files
• Comments generated: 4

[Copilot]

Copilot's findings

Comments suppressed due to low confidence (1)

src/Microsoft.ComponentDetection.Detectors/helm/HelmComponentDetector.cs:224

• TryRegisterImageReference is called without a logger here as well, so invalid reconstructed references (e.g., unexpected registry/repository combinations) will be skipped silently. Pass this.Logger to surface parse failures as warnings.

        {
            imageRef = $"{imageRef}@{digest}";
        }

        DockerReferenceUtility.TryRegisterImageReference(imageRef, recorder);
    }

• Files reviewed: 8/8 changed files
• Comments generated: 2

[Copilot]

Copilot's findings

• Files reviewed: 8/8 changed files
• Comments generated: 2

[Copilot]

Copilot's findings

• Files reviewed: 8/8 changed files
• Comments generated: 3

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.0%. Comparing base (9582bca) to head (64692bd).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff      @@
##   main   #1796   +/-   ##
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