config_builder+rpcwallet: add full net params

As a preparation for parsing addresses, we need the full network
parameters and not just the coin type in the RPC wallet.

config_builder.go

@@ -691,7 +691,7 @@ func (d *RPCSignerWalletImpl) BuildChainControl(
 
 	rpcKeyRing, err := rpcwallet.NewRPCKeyRing(
 		baseKeyRing, walletController,
-		d.DefaultWalletImpl.cfg.RemoteSigner, walletConfig.CoinType,
+		d.DefaultWalletImpl.cfg.RemoteSigner, walletConfig.NetParams,
 	)
 	if err != nil {
 		err := fmt.Errorf("unable to create RPC remote signing wallet "+