MOBILE-4362 comments: Fix delete button displayed when it shouldn't

The show delete button icon now also changes so it's clearer that something happened, otherwise if you cannot delete any of the comments you see it could seem that the button does nothing

src/core/components/message/message.html

@@ -31,12 +31,12 @@
             <ion-icon *ngIf="message.pending" name="fas-clock" [attr.aria-label]="'core.notsent' | translate" role="status"></ion-icon>
         </div>
 
-        <ion-button *ngIf="showDelete && !message.deleted && message.delete !== false" fill="clear" [@coreSlideInOut]="'fromRight'"
-            color="danger" (click)="delete($event)" [attr.aria-label]="'addon.messages.deletemessage' | translate" class="delete-button">
+        <ion-button *ngIf="showDelete && !message.deleted && message.delete" fill="clear" [@coreSlideInOut]="'fromRight'" color="danger"
+            (click)="delete($event)" [attr.aria-label]="'addon.messages.deletemessage' | translate" class="delete-button">
             <ion-icon name="fas-trash" slot="icon-only" aria-hidden="true"></ion-icon>
         </ion-button>
-        <ion-button *ngIf="showDelete && message.deleted" fill="clear" color="danger" (click)="undoDelete($event)"
-            [attr.aria-label]="'core.restore' | translate" class="delete-button">
+        <ion-button *ngIf="showDelete && message.deleted" fill="clear" [@coreSlideInOut]="'fromRight'" color="danger"
+            (click)="undoDelete($event)" [attr.aria-label]="'core.restore' | translate" class="delete-button">
             <ion-icon name="fas-rotate-left" slot="icon-only" aria-hidden="true"></ion-icon>
         </ion-button>
     </div>

src/core/features/comments/pages/viewer/viewer.html

@@ -12,7 +12,8 @@ <h1>
         <ion-buttons slot="end">
             <ion-button *ngIf="canDeleteComments" slot="end" fill="clear" (click)="toggleDelete()"
                 [attr.aria-label]="'core.toggledelete' | translate">
-                <ion-icon name="fas-pen" slot="icon-only" aria-hidden="true"></ion-icon>
+                <ion-icon *ngIf="!showDelete" name="fas-pen" slot="icon-only" aria-hidden="true"></ion-icon>
+                <ion-icon *ngIf="showDelete" name="fas-check" slot="icon-only" aria-hidden="true"></ion-icon>
             </ion-button>
             <core-context-menu>
                 <core-context-menu-item [hidden]="!(commentsLoaded && !hasOffline)" [priority]="100" [content]="'core.refresh' | translate"