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/micropython/native_misc.py

@@ -4,10 +4,13 @@
 @micropython.native
 def native_test(x):
     print(1, [], x)
+
+
 native_test(2)
 
 # check that GC doesn't collect the native function
 import gc
+
 gc.collect()
 native_test(3)
 
@@ -15,17 +18,23 @@ native_test(3)
 @micropython.native
 def f(a, b):
     print(a + b)
+
+
 f(1, 2)
 
 # native with 3 args
 @micropython.native
 def f(a, b, c):
     print(a + b + c)
+
+
 f(1, 2, 3)
 
 # check not operator
 @micropython.native
 def f(a):
     print(not a)
+
+
 f(False)
 f(True)