[ADF-5460] Add placeholder to SearchTextInputComponent (#7208)

docs/core/components/search-text-input.component.md

@@ -40,6 +40,7 @@ Displays a input text that supports autocompletion
 | searchTerm | `string` | "" | Search term preselected. |
 | collapseOnBlur | `boolean` | "true" | Toggles whether to collapse the search on blur. |
 | showClearButton | `boolean` | "false" | Toggles whether to show a clear button that closes the search. |
+| placeholder | `string` | "" | Placeholder text to show in the input field |
 
 ### Events
 

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

@@ -18,6 +18,7 @@
                    [autocomplete]="getAutoComplete()"
                    id="adf-control-input"
                    [(ngModel)]="searchTerm"
+                   [placeholder]="placeholder"
                    (focus)="activateToolbar()"
                    (blur)="onBlur($event)"
                    (keyup.escape)="toggleSearchBar()"

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

@@ -84,6 +84,10 @@ export class SearchTextInputComponent implements OnInit, OnDestroy {
     @Input()
     showClearButton: boolean = false;
 
+    /** Placeholder text to show in the input field */
+    @Input()
+    placeholder: string = '';
+
     /** 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