imports: sort imports everywhere in Spack (#24695)

* fix remaining flake8 errors

* imports: sort imports everywhere in Spack

We enabled import order checking in #23947, but fixing things manually drives
people crazy. This used `spack style --fix --all` from #24071 to automatically
sort everything in Spack so PR submitters won't have to deal with it.

This should go in after #24071, as it assumes we're using `isort`, not
`flake8-import-order` to order things. `isort` seems to be more flexible and
allows `llnl` mports to be in their own group before `spack` ones, so this
seems like a good switch.

lib/spack/llnl/util/tty/log.py

@@ -13,15 +13,14 @@
 import os
 import re
 import select
+import signal
 import sys
 import traceback
-import signal
 from contextlib import contextmanager
-from six import string_types
-from six import StringIO
-
-from typing import Optional  # novm
 from types import ModuleType  # novm
+from typing import Optional  # novm
+
+from six import StringIO, string_types
 
 import llnl.util.tty as tty