Enabling the hardened runtime also enables library validation, which
means that the manifest generator may not be able to load the built
plugin if the generator runs before the signing step.

The manifest generator tools should not be distributed/archived, so
disabling the hardened runtime for these targets is appropriate.

This reverts commit 82377a787a.

Reintegrates changes from cf9fc84669

JUCE no longer depends on built artifacts of the AAX_SDK

This reverts commit 4deea8ed93.

abspath doesn't cope very well with paths that contain spaces, even if
those spaces are escaped.

Xcode 14 has minimum deployment targets of macos 10.13 and iOS 11.

Mirrors the behaviour of CMake by only adding signing identity field to
project when identity is not empty.