Create per-package changelogs

[drahnr]

Providing functionality similar to git-cliff to extract meaningful changelogs on a per-package level would be nice feature addition.

Impl details:

Every git commit contains sufficient information to map itself to any of the n-crates present in the workspace, and hence a view on the global git changelog could be created.

Nice to have:

Allow integration with the README generation to always show the changelog vs the last major/minor/patch version.