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/import/module_getattr.py

@@ -10,13 +10,14 @@ except AttributeError:
 
 # define __getattr__
 def __getattr__(attr):
-    if attr == 'does_not_exist':
+    if attr == "does_not_exist":
         return False
     raise AttributeError
 
+
 # do feature test (will also test functionality if the feature exists)
-if not hasattr(this, 'does_not_exist'):
-    print('SKIP')
+if not hasattr(this, "does_not_exist"):
+    print("SKIP")
     raise SystemExit
 
 # check that __getattr__ works as expected