Turn the GroupKey into a string that is composed of the matchers if the
path in the routing tree and the grouping labels.
Only hash it at the very end to ensure we don't exceed size limits of
integration APIs.
Building a hash over an entire set of alerts causes problems, because
the hash differs, on any change, whereas we only want to send
notifications if the alert and it's state have changed. Therefore this
introduces a list of alerts that are active and a list of alerts that
are resolved. If the currently active alerts of a group are a subset of
the ones that have been notified about before then they are
deduplicated. The resolved notifications work the same way, with a
separate list of resolved notifications that have already been sent.
This adds a new nflog package meant to replace provider.Notifies. It
has a central protobuf type package, which is also meant for usage for
other packages and the API.
The generated Go types are also the in-memory representation.