sync status eta (#1701)

* sync status eta

* other necessary changes

* feat: Enhance Sync ETA display mode

- Enhance block rate calculation with weighted averages(accounts for network flunctuations and sync speed of more recent blocks while calculating eta, basically giving us more accuracy)
- Add option to switch between ETA and blocks remaining display in display settings
- Add placeholder ETA while gathering block data

* chore: Listen to smaller changes in eta

---------

Co-authored-by: Omar Hatem <omarh.ismail1@gmail.com>
Co-authored-by: Blazebrain <davidadegoke16@gmail.com>

lib/src/screens/dashboard/widgets/sync_indicator.dart

@@ -20,7 +20,7 @@ class SyncIndicator extends StatelessWidget {
     return Observer(builder: (_) {
       final syncIndicatorWidth = 237.0;
       final status = dashboardViewModel.status;
-      final statusText = syncStatusTitle(status);
+      final statusText = syncStatusTitle(status, dashboardViewModel.settingsStore.syncStatusDisplayMode);
       final progress = status.progress();
       final indicatorOffset = progress * syncIndicatorWidth;
       final indicatorWidth = progress < 1

lib/src/screens/settings/display_settings_page.dart

@@ -1,5 +1,6 @@
 import 'package:cake_wallet/entities/fiat_currency.dart';
 import 'package:cake_wallet/entities/language_service.dart';
+import 'package:cake_wallet/entities/sync_status_display_mode.dart';
 import 'package:cake_wallet/generated/i18n.dart';
 import 'package:cake_wallet/src/screens/base_page.dart';
 import 'package:cake_wallet/src/screens/settings/widgets/settings_picker_cell.dart';
@@ -46,6 +47,15 @@ class DisplaySettingsPage extends BasePage {
                   _displaySettingsViewModel.setShowAddressBookPopup(value);
                 },
               ),
+              SettingsPickerCell<SyncStatusDisplayMode>(
+                title: S.current.sync_status_display_mode,
+                items: SyncStatusDisplayMode.values.toList(),
+                selectedItem: _displaySettingsViewModel.syncStatusDisplayMode,
+                onItemSelected: (SyncStatusDisplayMode mode) =>
+                    _displaySettingsViewModel.setSyncStatusDisplayMode(mode),
+                displayItem: (SyncStatusDisplayMode mode) => mode.title,
+                isGridView: false,
+              ),
               //if (!isHaven) it does not work correctly
               if (!_displaySettingsViewModel.disabledFiatApiMode)
                 SettingsPickerCell<FiatCurrency>(