Add a client for BankForks (#10728)

Also:
* Use BanksClient in solana-tokens

tokens/tests/commands.rs

@@ -1,18 +1,29 @@
-use solana_client::rpc_client::RpcClient;
+use solana_banks_client::start_tcp_client;
 use solana_core::validator::{TestValidator, TestValidatorOptions};
 use solana_sdk::native_token::sol_to_lamports;
 use solana_tokens::commands::test_process_distribute_tokens_with_client;
 use std::fs::remove_dir_all;
+use tokio::runtime::Runtime;
 
 #[test]
 fn test_process_distribute_with_rpc_client() {
-    let validator = TestValidator::run_with_options(TestValidatorOptions {
+    let TestValidator {
+        server,
+        leader_data,
+        alice,
+        ledger_path,
+        ..
+    } = TestValidator::run_with_options(TestValidatorOptions {
         mint_lamports: sol_to_lamports(9_000_000.0),
         ..TestValidatorOptions::default()
     });
-    let rpc_client = RpcClient::new_socket(validator.leader_data.rpc);
-    test_process_distribute_tokens_with_client(rpc_client, validator.alice);
 
-    validator.server.close().unwrap();
-    remove_dir_all(validator.ledger_path).unwrap();
+    Runtime::new().unwrap().block_on(async {
+        let mut banks_client = start_tcp_client(leader_data.rpc_banks).await.unwrap();
+        test_process_distribute_tokens_with_client(&mut banks_client, alice).await
+    });
+
+    // Explicit cleanup, otherwise "pure virtual method called" crash in Docker
+    server.close().unwrap();
+    remove_dir_all(ledger_path).unwrap();
 }