simple clustering support for loki.source.kubernetes_events

[captncraig]

This implements clustering by simply distributing each namespace (or the only namespace for all when "" is given) to a different node.

As I submit this I realize there could be a problem since the positions will be stored locally, so if the clustering changes, the new owner could try to catch up. That may need a little thought.

[rfratto]

As discussed offline, this is a case where grafana/alloy#399 would be a more appropriate solution rather than adding a clustering block to loki.source.kubernetes_events; it's not clear if even significantly large clusters have so much event volume that it makes sense to shard event handling across multiple nodes.

For now, we'll continue to defer deduplication of logs to Loki while we wait for grafana/alloy#399 to be available.

I'm closing this for now, but we can revisit later if our knowledge about loki.source.kubernetes_events changes.