Add support for cgmanifest

[pombredanne]

See https://github.com/search?q=org%3Amicrosoft+cgmanifest.json&type=code
https://github.com/microsoft/onnx-server-openenclave/blob/ae91aa27dbba69c610462319068865304cf7191f/cgmanifests/README.md#L2

This is a (proprietary?) format seen in MSFT open source repos. Doc is behind login at https://docs.opensource.microsoft.com/tools/cg/cgmanifest.html

See for instance:

• https://github.com/microsoft/azurelinux/blob/50e2132e5a911b049c1f3dd83786c8f3d2a58887/cgmanifest.json
• https://github.com/microsoft/winget-cli/blob/master/cgmanifest.json
• https://github.com/microsoft/vscode/blob/main/cgmanifest.json

And these scripts:

• https://github.com/microsoft/azurelinux/blob/592875ba994cf7fc55449f95bfcb3d26f618a50d/toolkit/scripts/update_cgmanifest.py
• https://github.com/search?q="cgmanifest.json"+language%3APython&type=code
• https://github.com/microsoft/onnxruntime-genai/blob/7aef327a36bc318f126c6d2703367b60595dd27b/cgmanifests/generate_cgmanifest.py#L153
• A schema? https://json.schemastore.org/component-detection-manifest.json
• https://github.com/Witekio/imx-iotcore/blob/5b8b59bc0f8c11282aaddfbd4247803420c894ac/external/build_cgmanifest.py#L26

And this related format:

• https://github.com/search?q=path%3A*%2FOSSREADME.json&type=code