[Gardening] Update all Python scripting to conform to the style guidelines enforced by the black code-formatting tool.

.flake8

@@ -0,0 +1,28 @@
+[flake8]
+
+filename =
+    *.py,
+    list_tests/lit.cfg,
+
+exclude =
+    .git,
+    __pycache__,
+
+    # Ignore non-Python directories.
+    Sources,
+    Tests,
+    utils,
+
+extend-ignore =
+    # The black tool treats slices consistently, the E203 warning is not PEP8
+    # compliant (https://github.com/psf/black#slices).
+    E203,
+
+    # Line breaks before binary operators are not explicitly disallowed in
+    # PEP8, rather it should be consistent throughout the project. The black
+    # tool puts them on new lines which is to be considered a best practice
+    # in the future.
+    W503,
+
+# 10% larger than the typical 80, conforms to the black standard.
+max-line-length = 88