This provides an improved user experience, allowing cursor movement
directly from the keyboard.

- Fixes an off-by-one error when navigating by rows, caused by treating
  the table header as a row. The table header now has the header
  accessibility role.
- Fixes a bug where reordering table columns would cause the table to
  become inaccessible.
- Fixes a bug where the screen reader would try to navigate hidden table
  columns.
- Fixes an issue where moving the VoiceOver cursor to a partially hidden
  cell would cause the focus to move to the table itself, rather than to
  the cell.

This issue made hosts not recognize the ARA capabilities of AU plugins.

This change avoids a situation where a standalone plugin's Audio/Midi
settings window could appear in a wrong position.

Using this new function a previous bug is avoided where transforms
were applied differently to drawable paths and text elements.

Before this commit it was possible for the plugin to transfer control
to its internal MessageThread and call
IComponentHandler::restartComponent() from it.

On Windows, when opening a plugin editor, destroying the plugin
instance, and then creating a new instance and opening its editor, the
plugin would crash because the VBlankDispatcher singleton could not be
recreated.

Previously opening a PopupMenu and then clicking somewhere outside
the application would cause the mouse button representation to be
stuck in a down state.