Add support for relay-based filtering in nostr queries.
Filters can now include a "relays" field. Optimal performance when
you include a kind as well:
{"relays":["wss://pyramid.fiatjaf.com/"], "kinds":[1]}
This corresponds to a `ndb` query like so:
$ ndb query -r wss://pyramid.fiatjaf.com/ -k 1 -l 1
using filter '{"relays":["wss://pyramid.fiatjaf.com/"],"kinds":[1],"limit":1}'
1 results in 0.094929 ms
{"id":"277dd4ed26d0b44576..}
Signed-off-by: William Casarin <jb55@jb55.com>
0f66e87faf