Swiftlint

This step generates the swiftlint report and saves it to a file in the bitrise deploy folder. It produces 2 environment variables, one with the report and the other one with the path to the report file. The first variable is useful if you want to p pass your report directly to somewhere, for example a Slack channel. The second variable is useful if you want to process the report file further, for example upload it to S3 or attach it to a pull request. Finally, this step is compatible with the Bitrise test reports add-on, so in case the linting fails, you can easily see the details there.