RFR: 8284542: Missing attribute for state of CheckBox in CheckBoxTreeItem

[Ambarish Rapte]

Issue:
CheckBoxTreeItem extends TreeItem and adds a CheckBox.
The state of this CheckBox is not visible to an accessibility client application.
If we analyze a simple program that contains a CheckBoxTreeItem using a windows application "Accessibility Insights for Window", we can notice that toggle state of CheckBox is not exposed.

Fix:
Include the [Toggle Control Pattern](https://learn.microsoft.com/en-us/windows/win32/winauto/uiauto-implementingtoggle) in Accessibility information of a CheckBoxTreeItem in addition to the patterns that are used for a TreeItem.

Verification:
On Windows: Do the following with and without the fix.
1. Run the sample program attached to JBS issue.
2. Launch "Accessibility Insights for Window"
3. Observe that patterns section for each item
4. Select / de-select the CheckBoxes and observe the patterns section for correctness of toggle state.

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Commit messages:
 - Add CheckBoxTreeItem role and TOGGLE_STATE attribute

Changes: https://git.openjdk.org/jfx/pull/1088/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1088&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8284542
  Stats: 109 lines in 5 files changed: 102 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jfx/pull/1088.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1088/head:pull/1088

PR: https://git.openjdk.org/jfx/pull/1088