This is a breaking change - see BREAKING-CHANGES.txt

This includes Carbon support

With this patch applied, the DemoRunner should build under MinGW, and be
(nearly) feature-complete compared to the MSVC build.

Specifically, when building with MinGW:
- Adds support for accessibility
- Fixes build issues in the juce_video module
- Fixes a link issue in the VST3 wrapper when VST3_CAN_REPLACE_VST2 is
  defined
- Adds support for the new-style native FileChooser
- Tidies up some other low-severity warnings

Known issues:
- Direct2D rendering is still not supported when building with MinGW due
  to ABI compatibilities.

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 patch also moves PluginHostType into juce_audio_processors in order
to allow hiding of function implementations.

Reports the correct host name for Apple hosts on M1 which host plugins
in a separate process.

Affected hosts are:
- Logic Pro
- GarageBand
- MainStage
- Final Cut Pro