refactor tx sending

Refactor sending evm txs so that we store the txs before sending
and are accepting of send errors. This avoids a scenario where
we send the tx, but still receive an error, perhaps because of
a bad connection or other problem with the rpc provider.

Implement a send queue so that the caller doesn't have to wait
for the send. This should speed up ticks in core if the rpc
provider is functional but slow to respond.

client/asset/eth/deploy.go

@@ -351,7 +351,11 @@ func (contractDeployer) nodeAndRate(
 		return nil, nil, nil, fmt.Errorf("error creating wallet: %w", err)
 	}
 
-	cl, err := newMultiRPCClient(walletDir, providers, log, chainCfg, 3, net)
+	creds, err := walletCredentials(chainCfg.ChainID, walletDir, net)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("error generating wallet credentials: %w", err)
+	}
+	cl, err := newMultiRPCClient(creds, providers, log, chainCfg, 3, net)
 	if err != nil {
 		return nil, nil, nil, fmt.Errorf("error creating rpc client: %w", err)
 	}