Data structures and domain logic for reading the Fluvio Package Index.
This crate is used by the plugin installer and the self-updater. It is capable of reading the index file in the Fluvio Package Registry in order to find the latest release versions of various components.
The two main use-cases for this are to allow the CLI to install plugins,
e.g. via fluvio install fluvio-cloud, and to give the CLI visibility
of new releases for itself and plugins.