Add option to not print skipped violations in ConsoleOutputFormatter

[lprzybylek]

These changes propose a new option that allows hiding skipped violations from the console formatter's output. For depfiles with a long baseline, it is hard to spot new violations amongst skipped ones.

[smoench]

@lprzybylek thank you for your contribution. This option would also be interesting for other formatters (e.g. TableOutputFormatter). Can you add this option to the AnalyzeCommand instead? I also would prefer report-skipped as option name to keep consistency with the other names.

[lprzybylek]

@smoench Sure. Do you think of something like this in AnalyzeCommand::execute?

        if (!$input->getOption(self::OPTION_REPORT_SKIPPED)) {
            $context = $this->getContextWithoutSkippedViolations($context);
        }

I wonder how it will affect other formatters. I'm new to this code, first time saw it on Friday, but for example baseline formatter wouldn't make much sense to be run without skipped violations. Should we handle this option in every affected formatter? Or do we assume people know what they're doing using this option?

[smoench]

No, I meant it can be implemented like AnalyzeCommand::OPTION_REPORT_UNCOVERED.
Can you add the option to the AnalyzeCommand and adjust the ConsoleOutputFormatter? I will adjust the other output formatters.

[smoench]

Thank you @lprzybylek!