Save settings to nostr

[mikedilger]

As a 3xxxx event kind, gossip-specific settings.

Non-gossip-specific data should be separate such as relay lists, contact lists and I think Mute lists should be a NIP-51 list. https://github.com/nostr-protocol/nips/pull/183/files#diff-0d42225c4bd69ef69ef24d2de380ff90ca763019d04692558a1b78adeda25d50