Add ability to print warnings when `failOnViolation: true` and `violationSeverity: error`

### New feature, improvement proposal

#### Currently

When there are errors and warnings, only errors are logged

#### Desired

Warnings should be logged, too

#### Current workaround

Add `consoleOutput: true`. However, this has the following undesired issues:

- No console format/colors
- It shows full path instead of relative path
- Errors appear again

Start by locating the handling of `failOnViolation`, `violationSeverity`, and the existing `consoleOutput` workaround in the Maven Checkstyle Plugin. Confirm how errors and warnings are currently logged; done means warnings also appear with the normal console format and relative paths, without duplicating errors.

Written by the indexing model from the issue text.