refactor: remove default data from search page

Closes #151

src/app/modules/data/list/search-page.html

@@ -14,17 +14,26 @@
       (ngModelChange)="searchStringChanged($event)"
       [(ngModel)]="queryText"
       showClearButton="always"
+      placeholder="{{ 'search.search_bar.placeholder' | translate }}"
     >
     </ion-searchbar>
   </ion-toolbar>
 </ion-header>
 
 <ion-content>
+  <div
+    [style.display]="!showDefaultData && !items && !loading ? 'block' : 'none'"
+  >
+    <ion-label class="centeredMessageContainer">
+      {{ 'search.instruction' | translate }}
+    </ion-label>
+  </div>
   <stapps-data-list
     id="data-list"
     [items]="items | async"
     [singleType]="singleTypeResponse"
     (loadmore)="loadMore()"
     [resetToTop]="queryChanged.asObservable()"
+    [loading]="loading"
   ></stapps-data-list>
 </ion-content>