Remove KVStorePersister and lightning-persister crate

Finally, we remove the superseded `KVStorePersister` trait and
`lightning-persister` crate.

Author: tnull

Cargo.toml

@@ -5,7 +5,6 @@ members = [
     "lightning-block-sync",
     "lightning-invoice",
     "lightning-net-tokio",
-    "lightning-persister",
     "lightning-storage",
     "lightning-background-processor",
     "lightning-rapid-gossip-sync"