Handle old way of variant listing too

[ofalvai]

Checklist

• I've read and followed the Contribution Guidelines
• step.yml and README.md is updated with the changes (if needed)

Version

Requires a PATCH version update

Context

Parsing multiple variants in the variant input was accidentally changed in #43. This PR adds support for parsing the old way of defining variants, we shouldn't have changed the existing behavior in a patch version.

Changes

Parse the variant list by splitting both by line breaks (the literal \n) and by the "\n" substring (this was the old behavior).

Investigation details

Defining a list of variants by line breaks works in both the workflow editor GUI and in raw YML, like this:

inputs:
  variant: |-
    fullDevelopDebug
    fullDevelopRelease
  module: app

Decisions