Description

The clang-formatter is able to format code in C/C++/Java but there was
no formatter support for python language. In this commit we add a new
Extensions YAPF Format that can format any valid python code. It also
accepts many configuration that can be set up by user in style.

In addition to this new formatter, the complete formatter code has been refactored.
Notable ideas included in refactoring are as follow:

• Add a generic code-formatter abstract class that can be used to add new formatters for other languages.
• Reuse code across formatters.
• Purge XXXXFormatter::check(), We report error at execution in formatters if any.

Related Issues / Pull Requests

Motivation and Context

To correctly format python codes

How Has This Been Tested?

Arch linux

Screenshots (if appropriate)

Checklist

• If the key of a setting is changed, the old attribute is updated or it is resolved in SettingsUpdater.
• If there are changes of the text displayed in the UI, they are wrapped in tr() or QCoreApplication::translate().
• If needed, I have opened a pull request or an issue to update the documentation.
• If these changes are notable, they are documented in CHANGELOG.md.

Additional text

Documentation PR at cpeditor/cpeditor.github.io#101