AudioProcessorParameterWithID pre-dates HostedAudioProcessorParameter,
which is why AudioProcessorParameterWithID was initially used for this
purpose.

Reintegrates changes from cf9fc84669

AUs are more likely to have 16 channels on a bus now that the 9.1.6
Atmos layout is available.

On Windows, broughtToFront may be called during the destructor of
VSTPluginHost, adding the window back into activeVSTWindows, leading to
a heap-use-after-free in vstHookWndProc.

This change means that broughtToFront will only reorder
activeVSTWindows; it will never add a window that's not already in the
list.

This allows paths that are prefixed with environment variables to behave
as expected. This is useful when scanning the default LV2 locations in
the AudioPluginHost on Windows.

Some hosts (e.g. REAPER) will attempt to instantiate plug-ins with 64
active channels, and JUCE can't represent this layout. In this case,
failing to convert between VST3/JUCE layouts is not a logical error, so
asserting is not appropriate.