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/extmod/framebuf2.py

@@ -4,14 +4,16 @@ except ImportError:
     print("SKIP")
     raise SystemExit
 
+
 def printbuf():
     print("--8<--")
     for y in range(h):
         for x in range(w):
-            print('%u' % ((buf[(x + y * w) // 4] >> ((x & 3) << 1)) & 3), end='')
+            print("%u" % ((buf[(x + y * w) // 4] >> ((x & 3) << 1)) & 3), end="")
         print()
     print("-->8--")
 
+
 w = 8
 h = 5
 buf = bytearray(w * h // 4)