Consume Bank in BankClient

This will allow BankClient to spin up a thread to use the Bank.
It'll also ease the transaction from BankClient to ThinClient since
it won't let you depend on Bank.

Drawback, you the transition from Bank to BankClient will be harder
because the Bank methods are inaccessible.

runtime/src/bank_client.rs

@@ -11,11 +11,11 @@ use solana_sdk::transaction::{self, Transaction};
 use solana_sdk::transport::Result;
 use std::io;
 
-pub struct BankClient<'a> {
-    bank: &'a Bank,
+pub struct BankClient {
+    bank: Bank,
 }
 
-impl<'a> AsyncClient for BankClient<'a> {
+impl AsyncClient for BankClient {
     fn async_send_transaction(&self, transaction: Transaction) -> io::Result<Signature> {
         // Ignore the result. Client must use get_signature_status() instead.
         let _ = self.bank.process_transaction(&transaction);
@@ -57,7 +57,7 @@ impl<'a> AsyncClient for BankClient<'a> {
     }
 }
 
-impl<'a> SyncClient for BankClient<'a> {
+impl SyncClient for BankClient {
     fn send_message(&self, keypairs: &[&Keypair], message: Message) -> Result<Signature> {
         let blockhash = self.bank.last_blockhash();
         let transaction = Transaction::new(&keypairs, message, blockhash);
@@ -103,8 +103,8 @@ impl<'a> SyncClient for BankClient<'a> {
     }
 }
 
-impl<'a> BankClient<'a> {
-    pub fn new(bank: &'a Bank) -> Self {
+impl BankClient {
+    pub fn new(bank: Bank) -> Self {
         Self { bank }
     }
 }
@@ -123,7 +123,7 @@ mod tests {
         let jane_pubkey = jane_doe_keypair.pubkey();
         let doe_keypairs = vec![&john_doe_keypair, &jane_doe_keypair];
         let bank = Bank::new(&genesis_block);
-        let bank_client = BankClient::new(&bank);
+        let bank_client = BankClient::new(bank);
 
         // Create 2-2 Multisig Transfer instruction.
         let bob_pubkey = Pubkey::new_rand();

runtime/src/system_instruction_processor.rs

@@ -284,7 +284,7 @@ mod tests {
 
         // Fund to account to bypass AccountNotFound error
         let bank = Bank::new(&genesis_block);
-        let bank_client = BankClient::new(&bank);
+        let bank_client = BankClient::new(bank);
         bank_client
             .transfer(50, &alice_keypair, &mallory_pubkey)
             .unwrap();