Extract client code in send_transaction_service into a new structure (#3423)

In order to be able to use new client code in the `SendTransactionService`, I need to wrap network-related code with the new structure ConnectionCacheClient.
To to that I also had to move some auxiliary code into separate files.

(cherry picked from commit 144925e)

Author: KirillLykov

Cargo.lock

@@ -458,7 +458,7 @@ pub async fn start_tcp_server(
                 &bank_forks,
                 None,
                 receiver,
-                &connection_cache,
+                connection_cache.clone(),
                 5_000,
                 0,
                 exit.clone(),

banks-server/src/banks_server.rs

@@ -377,7 +377,7 @@ impl JsonRpcRequestProcessor {
             &bank_forks,
             None,
             receiver,
-            &connection_cache,
+            connection_cache,
             1000,
             1,
             exit.clone(),
@@ -6486,7 +6486,7 @@ pub mod tests {
             &bank_forks,
             None,
             receiver,
-            &connection_cache,
+            connection_cache,
             1000,
             1,
             exit,
@@ -6760,7 +6760,7 @@ pub mod tests {
             &bank_forks,
             None,
             receiver,
-            &connection_cache,
+            connection_cache,
             1000,
             1,
             exit,

programs/sbf/Cargo.lock

@@ -479,7 +479,7 @@ impl JsonRpcService {
             &bank_forks,
             leader_info,
             receiver,
-            &connection_cache,
+            connection_cache,
             send_transaction_service_config,
             exit,
         ));

rpc/src/rpc.rs

@@ -11,6 +11,7 @@ edition = { workspace = true }
 
 [dependencies]
 crossbeam-channel = { workspace = true }
+itertools = { workspace = true }
 log = { workspace = true }
 solana-client = { workspace = true }
 solana-connection-cache = { workspace = true }

rpc/src/rpc_service.rs

@@ -1,6 +1,8 @@
 #![allow(clippy::arithmetic_side_effects)]
 pub mod send_transaction_service;
+pub mod send_transaction_service_stats;
 pub mod tpu_info;
+pub mod transaction_client;
 
 #[macro_use]
 extern crate solana_metrics;