Add Docker archive support to Linux scanner

[jasonpaulos]

Adds support for scanning Docker archive images (tarballs created by docker save) in the Linux container detector. Builds on #1708

[Copilot]

Pull request overview

Adds support for scanning Docker archive images (tarballs produced by docker save) in the Linux container detector by recognizing a new docker-archive: image reference prefix and routing it through the existing “local image” scanning flow.

Changes:

• Add ImageReferenceKind.DockerArchive and parse docker-archive: inputs in ImageReference.Parse.
• Treat Docker archives as local image inputs in LinuxContainerDetector and invoke Syft with a docker-archive: source.
• Add detector documentation and a unit test covering Docker archive scanning.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
test/Microsoft.ComponentDetection.Detectors.Tests/LinuxContainerDetectorTests.cs	Adds a unit test verifying Docker archive inputs are scanned and mapped into recorded components.
src/Microsoft.ComponentDetection.Detectors/linux/LinuxContainerDetector.cs	Routes DockerArchive through local-image validation and constructs the Syft source string for docker-archive scanning.
src/Microsoft.ComponentDetection.Detectors/linux/ImageReference.cs	Introduces DockerArchive kind and parses the docker-archive: prefix.
docs/detectors/linux.md	Documents docker-archive: usage under supported input formats.

[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 🙂

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.0%. Comparing base (e0ed239) to head (d652cc0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff      @@
##   main   #1711   +/-   ##
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