Allow gitlab ci to be detected

[BackEndTea]

Gitlab CI wasn't being detected by the CiDetectedErrorFormatter. This MR allows detection so that the CiDetectedErrorFormatter can be used for gitlab as well.

[ondrejmirtes]

AFAIK GitLab still only shows these results in paid tiers: https://docs.gitlab.com/ee/ci/testing/code_quality.html

That's why GitLab CI is not currently detected by default. Maybe it's part of GITLAB_FEATURES env variable, I'm not sure. If you research that and detect correctly then I'd merge that.

[alexbrouwer]

Gitlab expects the results in a JSON file which can the be passed as a "codequality" artifact. It will automatically be parsed and displayed. Where depends on the "tier" being used, but even the free version shows it as you can read here.

Currently I have to run the PHPStan analysis twice. Once the get results in a Gitlab format, once to get it in a human readable form.

phpstan: # ... script: - vendor/bin/phpstan analyse --no-progress --error-format=gitlab --memory-limit=2G --quiet > code_quality_phpstan.json || echo "PHPStan found errors, see below." - vendor/bin/phpstan analyse --no-progress --memory-limit=2G artifacts: reports: codequality: code_quality_phpstan.json

Automatically detecting Gitlab resolves the duplicate analysis, but would require choosing, or adding config for, the name of the output file.

[BackEndTea]

@alexbrouwer i created https://github.com/BackEndTea/phpstan-multiple-error-formatter this package to have multiple error formatters at once for my case. Perhaps it could work for you as well.