Add support for arm64 registers in minidump core file saving. (#72315)

This patch adds support for saving minidumps with the arm64
architecture. It also will cause unsupported architectures to emit an
error where before this patch it would emit a minidump with partial
information. This new code is tested by the arm64 windows buildbot that
was failing:

https://lab.llvm.org/buildbot/#/builders/219/builds/6868

This is needed following this PR:
https://github.com/llvm/llvm-project/pull/71772