feat: add event kind blacklist

Adds a list to the config where you can specify which event kinds to blacklist.
The blacklist check will run right after verifying that the pubkey is allowed
to post events to the relay.

config.toml

@@ -100,6 +100,11 @@ reject_future_seconds = 1800
 # backpressure to senders if writes are slow.
 #event_persist_buffer = 4096
 
+# Event kind blacklist. Events with these kinds will be discarded.
+#event_kind_blacklist = [
+#    70202,
+#]
+
 [authorization]
 # Pubkey addresses in this array are whitelisted for event publishing.
 # Only valid events by these authors will be accepted, if the variable