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Finally, we remove the superseded `KVStorePersister` trait and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"

lightning-persister/Cargo.toml

@@ -8,7 +8,6 @@ lightning = { path = "../lightning" }
 lightning-block-sync = { path = "../lightning-block-sync", features = [ "rest-client", "rpc-client" ] }
 lightning-invoice = { path = "../lightning-invoice" }
 lightning-net-tokio = { path = "../lightning-net-tokio" }
-lightning-persister = { path = "../lightning-persister" }
 lightning-storage = { path = "../lightning-storage" }
 lightning-background-processor = { path = "../lightning-background-processor", features = ["futures"] }
 lightning-rapid-gossip-sync = { path = "../lightning-rapid-gossip-sync" }