[ADF-2930] general purpose "Empty Page" component (#3296)

* empty content component

* fix selector name

* style fixes

* cleanup code

* docs for empty content

* update docs

* update docs

* use typography for icon

* layout fixes for Login (ported from ACA)

lib/core/datatable/components/datatable/datatable.component.html

@@ -1,7 +1,8 @@
 <div
     *ngIf="data" class="full-width"
     [class.adf-data-table-card]="display === 'gallery'"
-    [class.adf-data-table]="display === 'list'">
+    [class.adf-data-table]="display === 'list'"
+    [class.adf-data-table--empty]="isEmpty()">
     <div *ngIf="isHeaderVisible()" class="adf-datatable-header">
         <div class="adf-datatable-row" *ngIf="display === 'list'">
             <!-- Actions (left) -->