message: feat(add-wallet): disable button until coin-protocol is selected
diff: <ion-footer no-border>
  <ion-toolbar padding transparent>
  <ion-row justify-content-end>
  - <button id="btn-add-coins" default ion-button color="primary" round item-right (click)="addWallet()">
  + <button id="btn-add-coins" [disabled]="!selectedProtocol" default ion-button color="primary" round item-right (click)="addWallet()">
  Next
  </button>
  </ion-row>
  