Add provider label features

[wagoodman]

What would you like to be added:
A labeling system that allows end users to select providers to run by capability or description. Something like:

Select providers that have a label describing a capability:

$ vunnel list --label linux
alpine
rhel
centos
ubuntu
debian
wolfi
...

Signal to downstream consumers the state of a provider (labels with values):

$ vunnel list --label stable=true
alpine
amazon
oracle
...

Why is this needed:
This allows for automatic select (and exclusion) of vunnel providers for consumers (like grype-db) in a more automatic way without needing to update the grype-db exclusion list when new providers are added.