chore: add codespell support and make it fix few typos

[yarikoptic]

More about codespell: https://github.com/codespell-project/codespell . It detects (and can be used to fix) commonly made typos. There is a good number of them found in this codebase.

I personally introduced it to dozens if not hundreds of projects already and so far only positive feedback.

CI workflow has 'permissions' set only to 'read' so also should be safe.