tests: replace pycodestyle with black

Drop pycodestyle for code style checking in favor of black. Black is
much faster, stable PEP8 compliant code style checker offering also
automatic formatting. It aims to be very stable and produce smallest
diffs. It's used by many small and big projects.

Running checkstyle with black takes a few seconds with a terse output.
Thus, test-checkstyle-diff is no longer necessary.

Expand scope of checkstyle to all python files in the repo, replacing
test-checkstyle with checkstyle-python.

Also, fixstyle-python is now available for automatic style formatting.

Note: python virtualenv has been consolidated in test/Makefile,
test/requirements*.txt which will eventually be moved to a central
location.  This is required to simply the automated generation of
docker executor images in the CI.

Type: improvement
Change-Id: I022a326603485f58585e879ac0f697fceefbc9c8
Signed-off-by: Klement Sekera <klement.sekera@gmail.com>
Signed-off-by: Dave Wallace <dwallacelf@gmail.com>

docs/_scripts/includes_renderer.py

@@ -33,15 +33,14 @@ class ContentRenderer:
 
 
 class PluginRenderer(ContentRenderer):
-
     def _render_entry(self, output_file, entry):
         description = "<no-description-found>"
         # we use glob because a plugin can (ioam for now)
         # define the plugin definition in
         # a further subdirectory.
-        path = os.path.join(self.plugin_dir(), entry.name, '**')
+        path = os.path.join(self.plugin_dir(), entry.name, "**")
         for f in glob.iglob(path, recursive=True):
-            if not f.endswith('.c'):
+            if not f.endswith(".c"):
                 continue
             with open(f, "r", encoding="utf-8") as src:
                 for match in self.regex.finditer(src.read()):
@@ -56,7 +55,7 @@ class PluginRenderer(ContentRenderer):
         with open(fname, "w") as output_file:
             with os.scandir(self.plugin_dir()) as pdir:
                 for entry in sorted(pdir, key=lambda entry: entry.name):
-                    if not entry.name.startswith('.') and entry.is_dir():
+                    if not entry.name.startswith(".") and entry.is_dir():
                         self._render_entry(output_file, entry)