Reintegrates changes from cf9fc84669

This fixes an issue where the app icon would not be visible for
standalone plugin targets.

In order to display a WebKit based webview a plugin will deploy a
temporary standalone executable on the system and host the WebKit
instance inside that.

JUCE no longer depends on built artifacts of the AAX_SDK

The ARA_SDK contains unguarded is_lock_free calls. This change
allows us to enable ARA compilation on Linux.

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

This also fixes an issue where the requested font style could be
incorrectly overwritten.

Some hosts on Apple Silicon require that the entire bundle has a
well-formed signature, rather than just the plugin binary itself. This
patch checks whether the bundle signature is valid, and if it is not,
ad-hoc signs the bundle before copying.