Added code formatting with black or ruff

[nilaykumar]

Use M-x ob-python-extras-format to format code blocks (supports ruff and black).

• DONE format src-edit buffers
• DONE format src-blocks outside of src-edit buffers
• DONE format using black or ruff, optionally via

(use-package! ob-python-extras
  :config
  (setq ob-python-extras-formatter "ruff"))

• DONE do nothing if code block is not lang python
• DONE learn some emacs-lisp to consolidate the ruff and black functions (ruff takes "format" as the first argument whereas black takes no arguments)
• DONE formatter can be set to run on code block execution by modifying the appropriate hook (add-hook 'org-babel-after-execute-hook 'ob-python-extras-format)
• DONE ensure that formatters are using their configs (e.g. checking pyproject.toml/ruff.toml/etc. if necessary)
• DONE remove "Wrote /tmp/babel-RRecW4/ob-python-extras-formatOBqumF" messages every time format is run
• DONE add documentation to the README

[ElleNajt]

Thanks for the pull request and the work on this project! :)

Here are my thoughts:

1. My main concern right now is that some of these functions are replicating functionality of existing emacs packages, and I think it would probably be better to rely on them.

For instance, to format a buffer with black, there's already the (python-black-buffer)
function from the 'python-black package, which gets installed in doom with :editor format and python enabled in init.el.

We could use it like this:

(require 'python-black)

(defun ob-python-extras--format-src-block ()
  "Format the current org babel Python source block using python-black.
Creates a temporary buffer, sets python-mode, applies formatting, and copies back."
  (interactive)
  (let* ((element (org-element-at-point))
         (language (org-element-property :language element))
         (orig-code (org-element-property :value element)))
    (when (string= language "python")
      (let ((formatted-code
             (with-temp-buffer
               (insert orig-code)
               (python-mode)
               (python-black-buffer)
               (buffer-string))))
        (save-excursion
          (goto-char (org-element-property :begin element))
          (org-babel-update-block-body formatted-code))))))

(add-hook 'org-babel-after-execute-hook 'ob-python-extras--format-src-block)

For ruff -- I haven't tried this package, but perhaps this: https://github.com/JoshHayes/emacs-ruff-format/blob/main/ruff-format.el ?

Both python-black and ruff-format rely on https://github.com/purcell/emacs-reformatter/blob/master/reformatter.el

2. In terms of configuration, my inclination would be to default to the chosen formatter for python buffers.

What do you think about this?