When opening the "settings" menu of Arturia Pigments VST2, the editor
window would move itself over the JUCE non-native titlebar in the
AudioPluginHost. Then, when the editor was moved back into the correct
location, the titlebar would not be redrawn, leaving it in an incorrect
state.

This change forces a repaint of the editor's peer whenever the size
changes, forcing the titlebar to repaint after the editor has moved.

This fixes an issue where specifying an audio device type before calling
initialise could cause a different device to become active, even if the
requested device type had usable devices.

With this change in place, a new device type will only be selected if
the current device type has no devices.

This fixes an issue where the editor of VocAlign Project 5 would fail to
open in the AudioPluginHost.

This change allows mouse events (including enter and exit events) to
reach unfocused views on macOS. This matches the behaviour of unfocused
windows on Linux and Windows, where components paint in their "hovered"
states even when the application window is in the background.

As a byproduct of using tracking areas on macOS, we can remove the fake
mouse move generator.

This new factoring is a bit more typesafe, as it avoids casting
internals to void*.

It also allows cursors to scale appropriately on high resolution
displays on Windows.