Add flag to get different result codes on warning/error

[SchweizS]

Expected Behavior

add a strict mode which changes the result codes:

result codes:

• 0 success
• 1 runtime error (e.g. invalid config)
• 2 linter warning
• 3 linter error

Current Behavior

currently there is no simple way (without looking at the output) to check if there was a warning.

result codes:

• 0 success / linter warning
• 1 runtimer error / linter error

Affected packages

• cli
• core
• prompt
• config-angular

Possible Solution

1. Add a cli-option to enable strict mode.
2. exit with 2/3 if there are warning/errors present

Context

gitlab ci job, which shows a warning for specific exit codes.

commitlint:
  [...]
  script:
    - npx commitlint
  allow_failure:
    exit_codes:
      - 2