[ADF-1039] Search results highlighting (#2080)

* Provide a way to highlight the searched word

* Add unit test

demo-shell-ng2/app/components/search/search-bar.component.html

@@ -1,6 +1,7 @@
 <alfresco-search-control *ngIf="isLoggedIn()"
                          [searchTerm]="searchTerm"
                          [autocomplete]="false"
+                         [highlight]="true"
                          (searchSubmit)="onSearchSubmit($event);"
                          (searchChange)="onSearchTermChange($event);"
                          (expand)="onExpandToggle($event);"