To take advantage of the excellent work that Google have done with
https://deps.dev we should make it possible to generate data from the
API.

For now, we'll pick up CVEs and licensing information as detected by
deps.dev, and in the future consider other metadata.

To start with, we'll use the RESTful API, and in the future migrate to
the gRPC API.

This bootstraps a new `repository` for the type, as well as a command to
generate the underlying data via the API.

To make this a little more efficient, we can introduce concurrency (with
a limit of Goroutines[0], as it is easy to hit OS limits) to go through the
(potentially very large) list of dependencies.

We'll look at renaming this in the future if it makes sense.

As mentioned in #77, this works best if the data available has the
available updates for Renovate.

Closes #66.

[0]: https://stackoverflow.com/questions/25306073/always-have-x-number-of-goroutines-running-at-any-time