macOS does not allow unix socket creation in private temp directories,
but global /tmp is ok, so swap out for global temp for now.
Updates #7658
Updates #7785
Signed-off-by: James Tucker <jftucker@gmail.com>
The intent of atomicfile is to overwrite regular files. Most use cases
that would overwrite irregular files, unix sockets, named pipes,
devices, and so on are more than likely misuse, so disallow them.
Fixes#7658
Signed-off-by: James Tucker <james@tailscale.com>