Standardize on Black for Python code in mozilla-central.

Allow-list all Python code in tree for use with the black linter, and re-format all code in-tree accordingly.

To produce this patch I did all of the following:

1. Make changes to tools/lint/black.yml to remove include: stanza and update list of source extensions.

2. Run ./mach lint --linter black --fix

3. Make some ad-hoc manual updates to python/mozbuild/mozbuild/test/configure/test_configure.py -- it has some hard-coded line numbers that the reformat breaks.

4. Add a set of exclusions to black.yml. These will be deleted in a follow-up bug (1672023).


Differential Revision: https://phabricator.services.mozilla.com/D94045

components/style/counter_style/update_predefined.py

@@ -17,16 +17,18 @@ def main(filename):
         or 'data-dfn-for="<counter-style>"' in line
     ]
     with open(filename, "wb") as f:
-        f.write("""\
+        f.write(
+            """\
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 predefined! {
-""")
+"""
+        )
         for name in names:
             f.write('    "%s",\n' % name)
-        f.write('}\n')
+        f.write("}\n")
 
 
 if __name__ == "__main__":