Initial implementation of VcpkgDetector and VcpkgComponent

[ras0219-msft]

This PR contains an initial implementation of detecting SPDX files produced by vcpkg. This depends upon experimental features that are not yet released in the vcpkg tool. (microsoft/vcpkg-tool#296)

New Detector Checklist

• I have gone through the docs for creating a new detector here
• My new detector implements IDefaultOffComponentDetector
• I have created a PR to the verification repo with components that my new detector can find
• (If necessary) I have updated the Feature Overview table in the README

[ras0219-msft]

+@grvillic for review

[JamieMagee]

Moving this to draft for now. There's still an open question about a generic SPDX detector.

[grvillic]

Thanks for the contribution!

[grvillic]

Can we add tests for this new detector? See other detector test samples in Microsoft.ComponentDetection.Detectors.Tests.

[grvillic]

We need to add tests validating the new detector.

[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 🙂

[grvillic]

We don't need these curly brackets here. you will can just set the variable below without initializing it (without var)