tests: Format all Python code with black, except tests in basics subdir.

This adds the Python files in the tests/ directory to be formatted with
./tools/codeformat.py.  The basics/ subdirectory is excluded for now so we
aren't changing too much at once.

In a few places `# fmt: off`/`# fmt: on` was used where the code had
special formatting for readability or where the test was actually testing
the specific formatting.

tests/thread/thread_lock1.py

@@ -36,11 +36,11 @@ try:
         print(lock.locked())
         raise KeyError
 except KeyError:
-    print('KeyError')
+    print("KeyError")
     print(lock.locked())
 
 # test that we can't release an unlocked lock
 try:
     lock.release()
 except RuntimeError:
-    print('RuntimeError')
+    print("RuntimeError")