MinAlertLevel (or similar) should control exit code

[l0b0]

Check for existing issues

• Completed

Describe the feature

I configured Vale using pre-commit in a repo, and thought I had fixed everything once pre-commit stopped reporting issues. But as it turns out:

1. pre-commit hides output for successful hooks when run without --verbose. This is a reasonable default to avoid noise from linters not following the "no output means everything's good" guideline.
2. vale only returns a non-zero exit code on errors, not on MinAlertLevel and higher levels.

This was surprising, since I expected that if anything is alerted, there should be a non-zero exit code.

As for the implementation, changing MinAlertLevel to also control the exit code changes the semantics, which would necessitate a new version. On the other hand, adding a separate MinAlertLevelControlsExitCode flag or MinExitCodeLevel option (with the same possible values as MinAlertLevel and defaulting to error) is additional complexity.

The solution suggested in #575 seems to require kinda clunky implementation (based on this):

vale "$@" | awk 'BEGIN {status = 1} 1; END {if(/^✔/) status = 0; exit(status)}'

[bdovaz]

Same problem here...