Please add EditorConfig file

[spenserblack]

I'm considering working on #253, but my editor is defaults to tab indentation. A .editorconfig file can help make it easier to contribute to this repo.

(I'm not sure if discussions is the right place for this request, but I wasn't sure where else it should go 🤔)

[lowlighter]

Indeed it can be problematic when editor is configured to format on save.
I'll add one to avoid large diffs in pull requests when reviewing 👍

Otherwise, code is actually auto-formatted by GitHub actions when pushed on master to keep code styling consistent without annoying too much contributors by forcing the style in their PRs 🙂