Treeview is not accessible using JAWS 2020

[dakahn]

The is an issue collecting known problems using the JAWS screen reader on the experimental Treeview component.

Environment

JAWS 2020 on Firefox latest in Windows 10

Issues:

• The user is only told their place in the list when the list receives initial focus, but not as they're navigating through the list.
  Expectation here is something closer to the functionality seen in a multiselect where the user is updated on their position as they navigate

• Hitting enter or space bar selects the focused list item and does not toggle open/close when nested lists are present
  The expected on click event for a tree view node with a sub-node is to toggle open/close state on enter or space

• The reader does not describe list items with nested lists as opened or closed when they receive focus.
  Expected behavior is for a list item with nested children to always describe it's current state: open or closed

• When the Treeview receives focus the entire component (lists and all child lists) are read in their entirety
  The Treeview label should be read, and individual list items should then be read as they receive focus

[dakahn]

closing in favor of #6792