Handle Chained Fixups

[kabiroberai]

MachO binaries built to target the latest betas (iOS 15/macOS 12/etc) – or, if built for arm64e, even some older versions – replace the old fixup format with a new, more compact, "chained" format. The new format is documented in <mach-o/fixup-chains.h>, and there's also a Medium article that summarises it.

This change, in conjunction with our discussion from #13, makes me think that it might be best if MachO-Kit provided an API to query an MKPointer and "resolve" it (either returning the resolved address if found, or otherwise metadata about the symbol) if it has an associated fixup, to abstract the implementation details of the fixups themselves.