Prefer YAPF over autopep8

[masad-frost]

YAPF is a real formatter where-as autopep8 is more of a lint fixer. See the YAPF readme https://github.com/google/yapf, see also discussion here palantir/python-language-server#328

The other reason is that I will be improving YAPF support, starting with adding support for protocol's formatting options (see #134) and then following up with sending actual text edits using yapf unidiff output format instead of the whole document https://github.com/python-lsp/python-lsp-server/blob/develop/pylsp/plugins/yapf_format.py#L49-L58

[ccordoba12]

Hey @masad-frost, thanks for your contribution! You said:

YAPF is a real formatter where-as autopep8 is more of a lint fixer

That's open to debate, but we consider Autopep8 provides simpler formatting than Yapf (or Black, for that matter). So, we don't plan to change the default formatter here, sorry.

However, please note that these are only default options and they can be very easily changed from your editor or IDE by disabling the Autopep8 plugin and activating the Yapf one. Basically, each plugin can be enabled/disabled by sending the appropriate request from the client.

[masad-frost]

It's all good. Thank you!