refreshBalance method
Fetches current balances from the wallet provider immediately.
Implementation
Future<List<WalletBalance>> refreshBalance(String walletId) async {
await _initializationFuture;
final wallet = await _getWalletForOperation(walletId);
final provider = _providers[wallet.type];
if (provider == null) {
throw StateError('No provider registered for wallet type ${wallet.type}');
}
final balances = await provider.getBalances(wallet).first;
_walletsBalances[walletId] = balances;
_walletBalanceStreams[walletId]?.add(balances);
_updateCombinedStreams();
return balances;
}