Improving the server mode

[prabhu]

cdxgen has a server mode when run with the --server argument. A single endpoint called /sbom is exposed to generate and retrieve an SBoM closely mimicking the cli.

The server mode could be enhanced to offer more APIs to work with the cdx data.

• /licenses endpoint to fetch license information.
• /evidences endpoint to present usage and call stack evidence of the components.
• /annotations endpoint to add or retrieve annotations.
• /services endpoint to present the services, endpoints, and data flow identified from the application.

This API approach would help:

• reduce the size of the cdx data transmitted by offering only the required information.
• improve performance by offloading expensive operations such as the gathering of evidence and services to a background worker threads

Thanks, @stevespringett, for the idea!