Read and write a LC_NOTE "addrable bits" for addressing mask

This patch adds code to process save-core for Mach-O files which
embeds an "addrable bits" LC_NOTE when the process is using a
code address mask (e.g. AArch64 v8.3 with ptrauth aka arm64e).
Add code to ObjectFileMachO to read that LC_NOTE from corefiles,
and ProcessMachCore to set the process masks based on it when reading
a corefile back in.

Also have "process status --verbose" print the current address masks
that lldb is using internally to strip ptrauth bits off of addresses.

Differential Revision: https://reviews.llvm.org/D106348
rdar://68630113