[Mac] Add a crash key containing System Integrity Protection state

There have been several confusing crashes in the last few months where
knowing that SIP was a factor would have made them easier to
investigate.

System Integrity Policy is available via the private
`csr_get_active_config` system call, with CSR standing for Configurable
Security Restrictions. The raw policy value is logged along with two
specific flags that are of interest.

Change-Id: Ie92dad97308155a75416740edfba926b513b8a31
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6174054
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Mark Rowe <markrowe@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1406432}