Optimization: detect overlapping filters

[jb55]

Let's say you create 3 columns:

1. Home timeline
2. Notifications
3. Global timeline

We should be able to detect that we only need 1 network subscription:

• Global timeline

And the remaining timelines can just be nostrdb subscriptions.

[jb55]

I think this only really makes sense in the subscription pool model. Not sure if this makes sense in the outbox model.

[jb55]

@v0l mentinoed they have something similar in rust for snort