supports multiline output

[pjxiao]

• Fixes Multiline outputs support in the GitHub action  #936
• Supports multiline output

Thank you so much for your work maintaining yq

[pjxiao]

This escape logic comes from a Github support case

[mikefarah]

bash black magic 👍🏼

[mikefarah]

Cool thanks for the PR - happy to merge this in, do you mind explaining how this works first though?

[pjxiao]

@mikefarah I appreciate your reply.

Suppose we have the following workflow:

jobs:
  convert-to-json:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: This outputs multiline JSON
        uses: mikefarah/yq@v4.12.2
        id: yaml-to-json
        with:
          cmd: yq eval --output-format=json 'config.yml'

      - run: echo "${{ steps.yaml-to-json.outputs.result }}"  # Currently we get only the first line

In the example above, we try to convert a YAML to a mutiline JSON but outputs.result contains only the first line.
example: https://github.com/pjxiao/yq-action/runs/3577428434 (please see 'Only the first line is saved' step)

My patch allows us to get an entire output even if the output contains line-breaks.
example: https://github.com/pjxiao/yq-action/runs/3577428423 (please see 'The entire JSON is saved' step)

The escaping logic:
The added escaping logic just URL encodes %, CR and LF. This originates in a community post. Though I researched documentations and references 1, I couldn't find any mentions of ecaping. So this behaviour is an internal specification.