Add missing websocket methods to rust RPC PubSub client (#21065)

- Added accountSubscribe,  programSubscribe, slotSubscribe and rootSubscribe to rust RpcClient
 - Removed duplication on cleanup threads
 - Moved RPCVote from rpc/ to client/rpc_response

client/src/rpc_response.rs

@@ -286,6 +286,14 @@ pub struct RpcIdentity {
     pub identity: String,
 }
 
+#[derive(Serialize, Deserialize, Clone, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct RpcVote {
+    pub slots: Vec<Slot>,
+    pub hash: String,
+    pub timestamp: Option<UnixTimestamp>,
+}
+
 #[derive(Serialize, Deserialize, Clone, Debug)]
 #[serde(rename_all = "camelCase")]
 pub struct RpcVoteAccountStatus {