Merge pull request #7592 from IgniteUI/state-support-hiergrid-master

Add support for IgxHierarchicalGrid and IgxTreeGrid and for Expansion states in state directive

Author: zdrawku

CHANGELOG.md

@@ -9,6 +9,9 @@ All notable changes for each version of this project will be documented in this
     - **Behavioral Change** - Change default positioning strategy from `ConnectedPositioningStrategy` to `AutoPositionStrategy`. The [`Auto`](https://www.infragistics.com/products/ignite-ui-angular/angular/components/overlay_position.html#auto) strategy will initially try to show the element like the Connected strategy does. If the element goes out of the viewport Auto will flip the starting point and the direction, i.e. if the direction is 'bottom', it will switch it to 'top' and so on. If after flipping direction the content goes out of the view, auto strategy will revert to initial start point and direction and will push the content into the view. Note after pushing the content it may hide the combo's input.
 
 ### New Features
+- `IgxGridState` directive
+    - Added support for expansion states, column selection and row pinning.
+    - Added support for `IgxTreeGrid` and `IgxHierarchicalGrid` (including child grids)
 - `IgxColumn`
     - Added `byHeader` parameter to the `autosize` method which specifies if the autosizing should be based only on the header content width.
 - `IgxToast`
@@ -51,6 +54,7 @@ All notable changes for each version of this project will be documented in this
 - `IgxHierarchicalGrid`
     - `onGridInitialized` - New output has been exposed. Emitted after a grid is being initialized for the corresponding row island.
 -  **Behavioral Change** - When moving a column `DropPosition.None` is now acting like `DropPosition.AfterDropTarget`.
+
 ## 9.1.0
 
 ### General