Add support for dynamic component pedigree

For components that a development team knows are modified, CycloneDX CLI should ideally be able to reach out into the VCS (git) and retrieve the commits that make a modified version unique.

This ticket is specific to `component/pedigree/ancestors` and `component/pedigree/commits`. Automated support for patches and resolves are outside the scope of this ticket.

Given the bom-ref of a modified component (and possibly the purl of the original component) the CLI should be able to construct the ancestors node and retrieve all commits and attach the pedigree node to the component.

This ticket was created as a result of a [Slack conversation](https://owasp.slack.com/archives/C6R3R32H4/p1615483811070800).

This ticket is related to #14.