Wait until transactions are confirmed, not merely sent.

Use `send_and_confirm_transaction` instead of `send_transaction_with_config`
as the former only returns once the transaction has been confirmed
(via the "finalized" strategy) or has timed out. The latter method only
sends the transaction in the _hopes_ that it will be confirmed, which, during
periods of high congestion, isn't a secure strategy.

helium-wallet/src/cmd/mod.rs

@@ -8,8 +8,7 @@ use helium_lib::{
     keypair::Keypair,
     message, priority_fee,
     solana_client::{
-        self, rpc_config::RpcSendTransactionConfig, rpc_request::RpcResponseErrorData,
-        rpc_response::RpcSimulateTransactionResult,
+        self, rpc_request::RpcResponseErrorData, rpc_response::RpcSimulateTransactionResult,
     },
     solana_sdk::transaction::VersionedTransaction,
     TransactionOpts,