[AAE-5715] support hint labels for search input (#7444)

lib/core/search-text/search-text-input.component.html

@@ -10,7 +10,7 @@
                 (keyup.enter)="toggleSearchBar()">
             <mat-icon [attr.aria-label]="'SEARCH.BUTTON.ARIA-LABEL' | translate">search</mat-icon>
         </button>
-        <mat-form-field class="adf-input-form-field-divider">
+        <mat-form-field class="adf-input-form-field-divider" [hintLabel]="hintLabel">
             <input matInput
                    #searchInput
                    [attr.aria-label]="'SEARCH.INPUT.ARIA-LABEL' | translate"

lib/core/search-text/search-text-input.component.ts

@@ -89,6 +89,10 @@ export class SearchTextInputComponent implements OnInit, OnDestroy {
     @Input()
     placeholder: string = '';
 
+    /** Hint label */
+    @Input()
+    hintLabel = '';
+
     /** Emitted when the search term is changed. The search term is provided
      * in the 'value' property of the returned object.  If the term is less
      * than three characters in length then it is truncated to an empty