Implement multiple webide tabs

src/app/webide/webide.component.html

@@ -1,5 +1,8 @@
-<input [(ngModel)]="filename">
-<button (click)="selectCode(); requestCode()" type="submit" class="btn btn-primary">Select file</button>
+<ul class="editor-tabs">
+  <li class="editor-li" *ngFor="let file of files">
+    <button class="editor-button" (click)="selectCode(file); requestCode();">{{file}}</button>
+  </li>
+</ul>
 
 <div
   ace-editor