Allow to ignore non-workspace dependencies

[haraldreingruber]

Checklist

• I have read the Contributor Guide
• I have read and agree to the Code of Conduct
• I have added a description of my changes and why I'd like them included in the section below

Description of Changes

• A config flag is added to ignore non-workspace dependencies, which is used for calling the builder.ignore_kind() method.
• The list of crates is added to the input of the handlebars template so that the list of third-party licenses can be displayed also by crate.
• The license text is added to the license summary/overview struct, so that the text for each kind of license can be displayed.
• The handlebars template used for the above mentioned use-cases has been added as an example in ./about_list_by_crate_example.hbs. Not sure if this is the best place, but the idea was that it might be useful to have this example somewhere?

Related Issues

This PR solves a problem similiar to the description in #144. After discovering that crates can be ignored by scope, I realized this is a nice way to achieve a similar result. If the intention is to generate a list of third-party crates and licenses, then non-workspace is probably even better compared to transitive dependencies which might include workspace crates (as they are usually not from a third-party).

[Jake-Shadle]

Thanks for the PR! I made one minor change and renamed the new config to ignore-transitive-dependencies.