refac balances and amounts

lib/globals.dart

lib/models/transaction.dart

lib/providers/duniter_indexer.dart

lib/providers/my_wallets.dart

lib/providers/substrate_sdk.dart

lib/providers/wallet_options.dart

lib/screens/myWallets/wallet_options.dart

lib/screens/myWallets/wallets_home.dart

lib/utils.dart

lib/widgets/balance.dart

lib/widgets/balance_display.dart

lib/widgets/payment_popup.dart

lib/widgets/transaction_in_progress_tile.dart

lib/widgets/transaction_tile.dart

lib/widgets/ud_unit_display.dart

lib/widgets/wallet_header.dart

pubspec.yaml