This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.

This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()

Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form

`    ResultTy DoFoo(Status& error)
`
to

`    llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?

The interesting changes are in Status.h and Status.cpp, all other
changes are mostly

` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.

This is an ongoing series of commits that are reformatting our Python
code. Reformatting is done with `black` (23.1.0).

If you end up having problems merging this commit because you have made
changes to a python file, the best way to handle that is to run `git
checkout --ours <yourfile>` and then reformat it with black.

RFC: https://discourse.llvm.org/t/rfc-document-and-standardize-python-code-style

Differential revision: https://reviews.llvm.org/D151460

Include the complete list of threads of all running processes
in the FreeBSDKernel plugin.  This makes it possible to inspect
the states (including partial register dumps from PCB) of all kernel
and userspace threads at the time of crash, or at the time of reading
/dev/mem first.

Differential Revision: https://reviews.llvm.org/D116255

Introduce a FreeBSDKernel plugin that provides the ability to read
FreeBSD kernel core dumps.  The plugin utilizes libfbsdvmcore to provide
support for both "full memory dump" and minidump formats across variety
of architectures supported by FreeBSD.  It provides the ability to read
kernel memory, as well as the crashed thread status with registers
on arm64, i386 and x86_64.

Differential Revision: https://reviews.llvm.org/D114911

This reverts commit aedb328a4dc9cb48ee3cf3198281649ea2c4f532.
I have failed to make the new tests conditional to the presence
of libfbsdvmcore.

Introduce a FreeBSDKernel plugin that provides the ability to read
FreeBSD kernel core dumps.  The plugin utilizes libfbsdvmcore to provide
support for both "full memory dump" and minidump formats across variety
of architectures supported by FreeBSD.  It provides the ability to read
kernel memory, as well as the crashed thread status with registers
on arm64, i386 and x86_64.

Differential Revision: https://reviews.llvm.org/D114911