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_stacksize1.py

@@ -6,20 +6,23 @@ import sys
 import _thread
 
 # different implementations have different minimum sizes
-if sys.implementation.name == 'micropython':
+if sys.implementation.name == "micropython":
     sz = 2 * 1024
 else:
     sz = 32 * 1024
 
+
 def foo():
     pass
 
+
 def thread_entry():
     foo()
     with lock:
         global n_finished
         n_finished += 1
 
+
 # reset stack size to default
 _thread.stack_size()
 
@@ -44,4 +47,4 @@ _thread.stack_size()
 # busy wait for threads to finish
 while n_finished < n_thread:
     pass
-print('done')
+print("done")