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/float/builtin_float_round.py

@@ -2,8 +2,18 @@
 
 # check basic cases
 tests = [
-    [0.0], [1.0], [0.1], [-0.1], [123.4], [123.6], [-123.4], [-123.6],
-    [1.234567, 5], [1.23456, 1], [1.23456, 0], [1234.56, -2]
+    [0.0],
+    [1.0],
+    [0.1],
+    [-0.1],
+    [123.4],
+    [123.6],
+    [-123.4],
+    [-123.6],
+    [1.234567, 5],
+    [1.23456, 1],
+    [1.23456, 0],
+    [1234.56, -2],
 ]
 for t in tests:
     print(round(*t))
@@ -17,7 +27,7 @@ for i in range(-1, 3):
     print(round(1.47, i))
 
 # test inf and nan
-for val in (float('inf'), float('nan')):
+for val in (float("inf"), float("nan")):
     try:
         round(val)
     except (ValueError, OverflowError) as e: