Allow for disabling auto-formatting with a global or buffer-local
variable, based on
62eba813b7/doc/recipes.md (autoformat-with-extra-features).
In the future, it would be interesting to do this based on the presence
of a file in the repository, such as `.do-not-auto-format`.
I've usually been against auto-formatting on save and instead preferred
to trigger it manually using its own keybinding.
I'm enabling it for now to see how I feel about it and I'll either keep
or revert it.