Added check all nulls to modify column Page (#10683) (#10751)

* -Added check all null checkbox

* Modified declarative table to add check all columns  in the column header

* -changed to using existing methods for firing events.

* -changed table height to auto
-center aligned data in table cell
-Check all generates event for only changed values

* -changes column header from text to column header (#10787)

* This fixes the weird angular stuff - we need to do this in every other component

* -added changes made by amir for dom object tracking
-added automatic checkall detection.
-made text-align center in table cells

* -fixed styling issues and issue with checkboxes

* -Removed unsued function

Co-authored-by: Amir Omidi <amomidi@microsoft.com>

src/sql/workbench/browser/modelComponents/media/declarativeTable.css

@@ -19,3 +19,10 @@
 	padding: 5px;
 	border: 1px solid;
 }
+
+.declarative-table-cell>checkbox {
+	float: left;
+	margin: 0 auto;
+	width: 100%;
+	text-align: center;
+}