LU-6142 misc: add editorconfig file

LU-6142 misc: add editorconfig file

EditorConfig is a unified configuration file recognized
by dozens of different text editors. This patch adds a
very simple config.

  https://editorconfig.org/

There is an upstream patch discussing editorconfig:

  https://lkml.org/lkml/2023/6/1/196

This patch aims to be much simpler. EditorConfig must
be enabled for many common editors (Emacs, Vim) and
is enabled by default (but can be disabled) for other
editors (NeoVim).

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I264377f96d6d155f92336083160a392edfc79a4f
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53211
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>