message: Alert when switching wallet storage option to none
  The user need to approve that wallet seed is saved
diff: @@ -331,6 +331,21 @@ export class ConfigureAppComponent implements OnInit {
  async updateWalletSettings() {
  const newStorage = this.selectedStorage;
  + const resaveWallet = this.appSettings.settings.walletStore !== newStorage;
  +
  + // ask for user confirmation before clearing the wallet cache
  + if (resaveWallet && newStorage === this.storageOptions[1].value) {
  + const UIkit = window['UIkit'];
  + try {
  + await UIkit.modal.confirm('<p class="uk-alert uk-alert-danger"><br><span class="uk-flex"><span uk-icon="icon: warning; ratio: 3;" class="uk-align-center"></span></span><span style="font-size: 18px;">You are about to <b>disable storage of all wallet data, which means there will be no wallet configured next time you use Nault</b>.</span><br><br><b style="font-size: 18px;">Before continuing, make sure you have saved the Nano seed and/or mnemonic of your current wallet</b>.<br><br><span style="font-size: 18px;"><b>YOU WILL NOT BE ABLE TO RECOVER THE FUNDS</b><br>without a backup of your currently configured wallet.</span></p><br>');
  + } catch (err) {
  + // pressing cancel, reset storage setting and interrupt
  + this.selectedStorage = this.storageOptions[0].value;
  + this.notifications.sendInfo(`Switched back to "Browser Local Storage" for the wallet data. Use the button again if you want to save other settings.`, {length: 10000});
  + return;
  + }
  + }
  +
  let newPoW = this.selectedPoWOption;
  const newMultiplier = this.selectedMultiplierOption;
  const pendingOption = this.selectedPendingOption;
  @@ -339,8 +354,6 @@ export class ConfigureAppComponent implements OnInit {
  minReceive = this.minimumReceive;
  }
  - const resaveWallet = this.appSettings.settings.walletStore !== newStorage;
  -
  // reload pending if threshold changes or if receive priority changes from manual to auto
  let reloadPending = this.appSettings.settings.minimumReceive !== this.minimumReceive
  || (pendingOption !== 'manual' && pendingOption !== this.appSettings.settings.pendingOption);
  