Support v2 of 'main bin spec' Mach-O LC_NOTE in corefiles

Version 2 of 'main bin spec' LC_NOTE allows for the specification
of a slide of where the binary is loaded in the corefile virtual
address space.  It also adds a (currently unused) platform field
for the main binary.

Some corefile creators will only have a UUID and an offset to be
applied to the binary.

Changed TestFirmwareCorefiles.py to test this new form of
'main bin spec' with a slide, and also to run on both x86_64
and arm64 macOS systems.

Differential Revision: https://reviews.llvm.org/D116094
rdar://85938455