Add `formatter` to `hx --health`

[kirawi]

https://github.com/helix-editor/helix/blob/5ae30f1993180b2c043d13f83e16f8647f7ff129/helix-term/src/health.rs needs to be modified.

[Sammo98]

Apologies, I missed the above PR when I created mine, first attempt at OSS. I believe the above PR though would not show the formatter column when hx --health is run and only when hx --health <lang> is run.