Projucer:  Fixed an assertion caused by the project content component trying to grab keyboard focus when not visible

Accessibility:  Added VoiceOver (macOS) and Narrator (Windows) accessibility screen reader support to juce_gui_basics

Previously, IEditController parameter indices were being used to index
into the AudioProcessor parameter array, but these parameter indices are
not guaranteed to point to the same parameter (parameter groups may
cause reordering on JUCE's side). Now, we use the IEditController
indices universally.

Previously, the following plugins were causing issues when hosting their
editors:

- Softube plugins. I used Saturation Knob for testing, which crashed when
  deleting the temporary parent view.
- KORG Gadget series, which displayed a black screen after the temporary parent
  view was deleted.
- FabFilter Pro-C, which displayed at the wrong scale when opened on a
  retina display.

Old PluginDescriptions may only have the `deprecatedUid` field set, with
the `uniqueId` field set to 0. In this case, the uniqueId should be
ignored, and the deprecatedUid used instead.

This change ensures that popup menus will be dismissed when hosted
plugin windows are moved, even when these plugin views are themselves
hosted inside JUCE views, like those used in the AudioPluginHost.

When drawing a popup menu for a target component with a non-unity scale,
the contents of the component were being drawn with an unwanted vertical
offset.

StandalonePluginHolder:  Fix out-of-bounds read when audio callbacks use larger-than-expected buffers

Projucer:  Fixed a potential crash in JucerTreeViewBase when dereferencing a deleted pointer to the underlying TreeViewItem