[editor] Fix cloze button tooltip in TextEditor

The tooltip declarations does not need escaped text. Was shawing one to 
many backslashes.

projects/editor/src/app/text-editor/rich-text-editor.component.html

@@ -222,11 +222,11 @@
     </mat-menu>
   </div>
   <div *ngIf="showCloseElements" fxLayout="row" fxLayoutAlign="space-around center" >
-    <button mat-icon-button matTooltip="\\i" [matTooltipShowDelay]="300"
+    <button mat-icon-button matTooltip="\i" [matTooltipShowDelay]="300"
             (click)="insertSpecialChar('\\i')">
       <mat-icon>text_fields</mat-icon>
     </button>
-    <button mat-icon-button matTooltip="\\z" [matTooltipShowDelay]="300"
+    <button mat-icon-button matTooltip="\z" [matTooltipShowDelay]="300"
             (click)="insertSpecialChar('\\z')">
       <mat-icon>drag_indicator</mat-icon>
     </button>