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/azdata.proposed.d.ts

@@ -100,6 +100,8 @@ declare module 'azdata' {
 		headerCssStyles?: { [key: string]: string };
 		rowCssStyles?: { [key: string]: string };
 		ariaLabel?: string;
+		showCheckAll?: boolean;
+		isChecked?: boolean;
 	}
 
 	export enum DeclarativeDataType {