set a formatter that fails (`"formatter": {"external": {"command":
"false"}}`), save, and you get nothing. it just goes to the log, the
"Formatting failed" indicator never shows.

#51605 made the formatter loop log-and-continue instead of bailing (so
unrelated edits don't get reverted, #51490). downside was the pipeline
always returned Ok after that, so the failure flag the indicator reads
always got wiped. this brings back failures from formatters you actually
configured. auto ones stay quiet when they're not around, so no prettier
installed = still a no-op.

only explicit failures show up, bit narrower than before #51605. can
widen it to auto ones too if you want, one line.

Fixes #59988.

Release Notes:

- Fixed formatter failures not showing the "Formatting failed" status
bar indicator

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>